Apologies in advance for the long post but don't want to drip feed info.

DS is coming up 18 and has already failed yr 11 twice (once he changed electives and repeated, this time they're letting him through to yr12).

He started school aged 4 (England) and was withdrawn due to physical intimidation from another child within 6mths. He was then homeschooled till he was 7 when he returned to full time formal education. He's never been interested in school, hates being told what to do and is incredibly defiant when it comes to homework.

His dad was violent and he left the day after his 9th birthday and hasn't had any contact since he was 10. When he was 11 my girlfriend moved in and when he was almost 14 we moved to Australia.

Since he's been old enough we've had problems with him completing homework - his pattern is to not tell us he has any (lie to our faces when we ask) and then lie to his teachers about why it hasn't been completed.

His first attempt at yr11 he selected the wrong electives and hated every minute of the year. We encouraged him to try again and accept that he'd made a mistake in his choices and he was happy to redo the yr with new subjects.

His second attempt at yr11 he only completed 1 piece of coursework (which he got 97% for) and didn't achieve higher than 27% in any of his exams. It's not that he can't do the work, it's just that he's lazy and doesn't see why it's important.

He is full of ideas about his future (that last a couple of weeks) and then he's off on another idea, which is nothing to do with his current subjects.

I've just had an email from his bio teacher telling me he's failed to hand in an assignment (due 18th November that I knew nothing about) and he's in the same situation with chemistry. He told his bio teacher the work was done but power outages meant he couldn't send it in. We haven't had any problems with the power and so far as I know it hasn't been completed.

The atmosphere in the house is horrendous, the girls (15 and 13) dread him coming back from school as he lies so openly and doesn't think twice about yelling at me and telling me I never believe him. It's hard to when he always lies

Has anyone else been in a similar situation? If so how did you handle it?