How do I deal with a seller that provides an extremely low quality model which is different from the pictures?

Hi,

I purchased some model, the renders on the product page were smooth, high quality, high poly count model renders. The model available for download after purchasing is exceedingly low on poly count, and it is not a low-poly type model.

I requested my money back and offered to hand over a signed document claiming I deleted all copies of model found on my property but received no answer. This is baffling to me, as the advertised product is not the one provided.

Thanks in advance for any help