if i was you i would just cut your losses and get someone proper to fix it if they will take it on,most plumbers wont go to other peoples work/cock ups.ive done good jobs and not been paid for the slightest thing had one were they didnt like the tiles they,d picked ,and wanted them swaping at my expence i said no ive got other work and couldnt do it and i didnt get paid the full amount and id saved them £2000 on meterials cos got them on my account,silly me ,ive learnt that one ,thats why i try not to do bathrooms anymore unless theres nothing else,anything under £5000 you wont get anything for, i went to a solicitor to get paid and was told this,you might win m8 in the small claims court but if he doesnt turn up or pay there nothing you can do sorry to tell ye this but been down this road but on rogue customer side,so i would just say clear of the bloke and the courts and learn from it and in future check peoples work first from work they,ve done may cost you some more money but better than paying out more for nothing