Agg. £1800. That's painful. Well done for keeping on going at it.
I'm really surprised you were failed for stalling the bike just once. Even the police are allowed to stall once in their training (although for them, it's once in five full days of riding ).
As for passing the car too close, you will do yourself a favour if you always keep a full car-door's length between you and any parked car. Doesn't make any sense to put yourself in the danger zone. But you may go closer if you know the car is empty.
When I failed my mod 1, I went to another trainer, and they were happy to take me through whatever training I needed to get me through mod 1 and 2 - it was about two extra lessons, that's all. I'd say move on and find someone who likes you and who'll give you the training you need. I'd suggest dropping in on them at the end of the day (4:30-5pm ish) for a quick chat if you can. You get a lot more feedback face to face.