ASD Spectrum

Hello I  have been bringing my nephew up since he was 10 months old and he is now 13.I have been fighting to get him assessed for 11 years and have finally got him on the spectrum even though it took drastic action to get there.He is a very young 13 and most people think he is about 9 as he comes across very immature.My biggest problem with him is electronics he will go to any lengths to get them to the extreme he stays awake all night so they have to be taken off him often and recently he stole a mobile phone from a friend house and I found it last night what had really kicked him off.i need some advice if I give him any form of electronic he kicks off when it's time to come off and he will steal to get it but if I don't give him them he will steal also so I really don't know what to do.His obsession is out of control my support worker is trying get best but it's so hard when one of the things he does is screeching at me all the time I'm so frustrated with it that I'm at the end of my tether with it I don't know what to do.I hope someone can help me with some advise Thank You.