Seller promises to deliver just half of the work and asks for 3/4th payment.

Hello,
I posted a job a few days ago and had specified all my requirements. Out of all the proposals I chose one seller and awarded the job after discussing all the details. I raised the amount a little so he would provide 8 rendered images and update the model with lighting and environment.
After a day or two of awarding the job, he said he'll provide just 4 images as he couldn't render the file in a particular software and had to use another software.
In the end he sent two rendered images which look photoshoped and not of the best quality. Also, I had told him not to start rendering as I had to make a few changes in the model but he rendered anyway and I won't be able to use these files anywhere.
I chose to cancel the job after all this rigmarole, but he's asking for 3/4th of the total amount. I agree he must have worked but the work he has provided (which is just a combined file of the models) is useless to me. I can't use the rendered images either.
He also accused me of fooling him and that I will eventually use the two rendered files fraudulently. This was a very disappointing experience on pph.

Please help me out. I don't know how to deal with this dramatic person who is playing to be the victimized. I certainly don't want to pay him because none of his work has been helpful and he didn't keep his word.