Advice needed.

Hey, needing some advice here.

Basically, I hired a good friend of mine to do me some Magento Integration. We agreed a price and I paid half upfront. I gave him 2 weeks to complete this. After 2 weeks, I gave him another week. After the 3 weeks, the integration is half done and he claims he can't do anything else because he doesn't know how. He refuses to pay the 50% down-payment back, because he's completed 50%(ish) of the work. I didn't hire him to do 50% of the work, so I think he should refund me the money. I've found someone else to start the work from scratch.

In the PayPal dispute, he says and I quote,

Send payment for the final 50%, and the final 50% of the work will be completed.

So now all of a sudden, he can complete the work? Makes me laugh.

I wont name names as I wouldn't want to affect his reputation because he is a genuinely good coder. If he wants to step in then that's fine. Shame because I've been good friends with him for about 3 years.