My gfs car has stoped working, it wont start, shes only had it for 2 months, its had 2 new batteries, first issue she had was sometimes when you took the key out the car stays on 2nd issue was the passanger seat belt warning light comes on when no one is sitting there, then the car wont start, took it to a garage they said it could be the ECU so it got sent off to be checked, it came back and it was fine, they have done loads of scans but cant find the fault???