Problem Client

I have this client who is refusing to pay me for work done to his site. The client approached my father for a main page upgrade, for which he was given a whole redesign of the site thrown in. I had nothing to do with the redesign, which went far outside the scope of work requested. The client only payed for a single page redesign. Not happy about that but it is fair. The client then went and changed hosting companies. HaHa. Not only did he lose his site, (he didn’t realise he had to download it and the reload it to the new server) he lost his email facilities for a few weeks too. Poor him. I managed to sort out his hosting problems by getting the keys redelegated to the new company after numerous emails to and fro betweeen the 2 ISP’s. Found and old version of his site and uploaded it for him. I charged him $150Au for my troubles. He paid. A couple of weeks later he rings me up and asks me to change some contact details for him. No worries, I say, do the ammendments and email him the page to upload. A couple of weeks later he gets back to me, saying there is a problem with his contract page still. Looking into it I realised that the validation and parsing was taking place on his existing host. So I go into his cpanel and setup the email form for him there. I change the redirection to his own site with a thankyou page, oh I and change his details cause he can’t work out how to upload a single page. For this I tried to charge him another $150 and he is refusing to pay, even though if he hadn’t changed hosts there would have been no problem. There is a company here in town who charge $600 to set up an email contact form (ludicrous I know) and $250 per new page. What do I do?