misunderstanding and complaints at work

If like me you are, proffesional, polite and to the point, then hold your head up high x

Would it be helpful to have a banner or some text on your email signature saying something positive around you being autistic? 

Very difficult situation when you are dealing with external customers.
I much prefer to work for internal customers - at least you can bring HR into any issues that arise from your autism.

I've been through the same, people call me rude and patronising because I focus on factual responses, and I start explanations without assuming any prior knowledge.

Nothing you can do to stop bosses doing this, they worry about losing customers, orders, income etc. 

All you can do is figure out how to cope, or find a less customer focused role 

I had similar where I used to work.
I was by far the most experienced person in the team that worked on a very niche area of IT.
In fact, they came into the team with zero experience and I was tasked with training them up.
I really struggled when they appeared disinterested, not engaged and simply not using their brains!

This was before I was diagnosed and my attitude was having a negative impact on the "team dynamic" (as my boss told me).
I got my diagnosis late last year and shared it with the team. At least they then realised that I was not being picking on them, instead it was typical in the way that an autistic person may communicate. There were a couple of reasonable adjustments put in place - one being reduced hours.

However, I think that the damage was already done, plus I have some other health conditions that mean that I have to take a lot of time off sick. This resulted in my employer putting a "settlement agreement" on the table which I had little choice bit to take it.

As you've been open with your employer and let them know about your autism, yet they haven't made any reasonable adjustments in the 4 years that they have known about it, then it may be that they never will make any adjustments.
Probably worth speaking to HR and arranging a meeting with them and your manager.
There could be the potential of discrimination / failure to make accommodations, but unless you have the strength and resources to go down the legal route (something that I seriously considered in my situation), then I'm afraid that maybe your working for the wrong company and you should look elsewhere. 

I had some similar issues. One day I sat with my team lead and together we prepared phrases for various most common situations. I saved them in Google spreadsheet and I used them to build emails to the customers. It really helped and saved me a lot of time. Only in some rare situations I had to ask someone to read and check my email to the customer. In my case I had no idea about any autism so I basically did not disclose anything nor asked for any accommodations. They just saw that I was very accurate and conscientious, but struggling with my soft skills. Asking someone for help is good, but it may be difficult for others to be available all the time. 

I wonder if someone there can proofread things for you before you send it. Is that an accommodation that the office can provide? I mean, if both you and the office want to work on improving the tone in your emails, I can't see why they wouldn't try to help you with that. They can just read it, and offer phrases that sound more polite. Or maybe they'll read it and find nothing wrong about it, and then even if the client complains about it, they'll know that the fault is not on you, but on the client. 

But it can be hard for others to proofread and give you feedback on things, especially because some people are not very polite when giving their feedback, but if the entire proofreading procedure is done to sound more polite in emails, then the proofreader should be polite about it to you as well. If they are not, they are missing the point. 

Mxanthrope said:

4 years ago I disclosed I'm autistic.  They have been very slow to make accommodations, though they say very nice things to my face.

As it has been 4 years since you disclosed (and the accommodations seem slow to have been implemented), I wondered; if you felt there was any possibility of the Human Resources Team being requested to neutrally facilitating a reasonable adjustments review?r

Ideas for a review:

- acknowledge what has worked well,

- define what has yet to work as well as had been anticipated

- after 4 years, might there now potentially be any new strategies or access to training topics (some in support of your goals, other awareness and inclusion training for for other people, plus maybe something relevant to everyone which might be researched and trialled before being incorporated into a.constructive refreshed plan?

What prompted me to wonder about the above - was when I read the "Reviewing Policies" section of this ACAS guidance document about reasonable adjustments (I realise the document mentions more about mental health than Autism - and yet, when you read that section; it seems equally relatable):

https://www.acas.org.uk/reasonable-adjustments-for-mental-health/reviewing-policies-with-mental-health-in-mind

I am relieved that, at least, they say nice things to your face (because that is crucial).

Wishing you well (your post did not come across to me as a rant - rather, you were telling it like it is from your perspective).  That is not to be overlooked by anyone - they are your feelings / emotions - that makes them valid, in my assessment of the situation.

I work in a job where there are some things that are right or wrong and particular rules. So I often have to state facts and people can complain about that. I have tried to develop friendly phrases to explain that unfortunately this is how it is. I used to just answer questions in a matter of fact way. I wonder if you can develop some phrases or start a letter or email by thanking them for contacting before answering and use phrases like unfortunately I am unable to consider your request without....