sounds like he will be trying the old money off,or not paying scam, if he or she is not happy with you,ask to be paid a fair agreed amount for what you've done so far and then he can get someone else,sounds like you would be better off out of it,do you think if hes that determined to cause a problem you will get paid?if not then dont continue,trouble is its a bit catch 22,you could do more days there and still not get paid ,but if you walk that gives him reason not to pay,so try to agree something and if you do continue ,get him to write down what he wants, i had a customer who ordered his own tiles and was about 3 m2 short so there was not enough to do toilet next door he then blamed me for using too many??!!!! he then insisted that he was paying me to fully tile so i had to do under shower tray and behind all the pipes behind the built in furniture,unbelievable,i had the mother daughter and father all stood there having a go, they insisted that the tile shop couldnt be wrong,its like banging you head against a brick wall,the daughter actually insisted she knew just as much as me about tiling at which point i said "your the best person to finish the job then arent you" packed my tools up and started to walk,they soon changed their tune when they saw i was serious,i finished the bathroom got paid and they said "when will you be back to do the toilet?",i wont tell you what i said but gave me great satisfaction!!