I too would have a face to face talk with him. If you paid for some of the mounts, he should complete the work or give them back with your money. The ones you didn't pay for yet I would suggest to just get them back. This way he won't have such a work load (from you) and you stand a better chance of getting the ones you did pay for completed.

I'd be more than happy to assist you in getting your money and mounts back.