well if your mate did the job, and it was how he was told to do it, then he shouldnt have to fork out. but if your mate really did make a mistake and he is at fault, then he should have to go back and fix the job to standards he was asked to do in the first place, or re do the whole job again. i mean if u are employed by some1 to do a job and you dont complete it to there specifications then u are a fault as far as im concerned.