Technology addiction in 12 year old

Hi all, 

My son is high functioning ASD and Aspergers and has recently started high school.  We have been having increasing issues over the last few years about his social development and mental development.  One of the biggest issues we have is that he is utterly obsessed with technology.  It has always been restricted and as a reward for good behaviour and working hard on school work etc, but last night we hit a new low.  He chose to leave the bathroom with faeces on his hands to get back to the Wii U, unbeknownst to us.  He then proceeded to help set the table for dinner and get plates etc out and it wasn't until we had finished dinner that his hands were noticed.  Needless to say we were all rather horrified.  

Given a choice over anything or tech, he will always choose tech.  He thinks of nothing else, you can't really have a conversation with him without him turning it to tech.  If there is a screen in a room, no matter what it is showing, he will keep taking his eyes to it instead of focusing on what he should be doing. He has no friends as he chooses to take himself away to use his school chromebook or goes to computer club at lunch times, uses his phone on the bus etc etc, the list goes on.  He refuses to do homework if he knows it won't lead to tech time, to the extent that he will sit at a table for hours and do nothing rather than do the work.  He openly says it is his life.

We have been looking at lots of research about addiction to screen time and the strong detrimental effects it can have on children with autism.  We have decided to follow the advice set out in the studies and try to eradicate screen time completely where possible.  He will be allowed to use his chromebook in lessons at school, but to the best of our ability this will be it (hard to police while he is at school). 

Has anyone else had any experience of tech addiction and successfully combated it or otherwise?