Any advice gratefully received

hi I'm new to the forum.  I'm the gran of an amazing 16 yr old  young man who was diagnosed at age of 12 with ASD.  Since then his life and ours has been a huge rollercoaster of emotions and anxiety.  He tried 3 mainstream  schools with predicatably awful results before recieving funding for am amazing school for boys just like him.  He's been attending since Jan of this year.  This year will be his GCSE year as he had missed so much school.  However we are still having huge verbally aggressive outbursts mainly aimed at my daughter ( his mother). She is a lone parent and we help as much as we can as we live nearby and we are a " safety valve" for our boy as things at home can become very intense.  He refuses to do anything at home even when asked.  He won't walk the dog, help in the house in any way, won't wash, shower clean his teeth or wear clean clothes.  He might clean himself up maybe once a week.  He has no friends at school or at home and is very isolated.  He does a attend a group for kids with Aspergers once a week and all he does is play football and not really I react with the others much.  He is totally immersed maybe addicted to an online computer game and this is all he does day and night.  My daughter has asked him to stop but he won't, doesn't see why he needs to.  She has turned off the internet only to experience very verbally aggressive bullying behaviour.  He will tell her if she turns it off he will not go to school.  In the past she has turned it off with not much success as he simply retreats into himself and refuses to go to school, to engage with family etc. Pretty much how he is when the internet is not turned off actually.  I could go on and on but we are all heartbroken and desperate to understand what's happening and why and how to fix it.  He is so nasty when he doesn't get his own way and it feels like he really doesn't care about anybody or anything just his game.  My daughter has discussed this with his consultant at CAHMs and she has explained to my grandson that this behaviour is not good for him and he needs to limit his time on games but he won't listen   The consultant says there is nothing else she can do.  We seem to be totally stuck with this destructive behaviour and just don't know what to do.  My daughter is on the verge of a breakdown as every morning they have the same awful routine of her asking him to get up and him saying in a minute then an hour later he's still not up.  He does come to stay with us just to change the dynamic a bit and we have the same behaviours too although we are luckier in the we can normally get him into the taxi to take him to school.  We are just so sad and devastated for our boy   Is there anyone who can help offer advice anything at all.  Thanks so much for reading this. I'm sure there are worse behaviours but this has been going in so long. We cannot have a reasonable discussion with him as he merely tells us what he thinks we want to hear and has no intention of keeping to any agreement.