This is one of the main reasons I avoid buying anything from Marketplace sellers on Amazon. One can argue if it is right or wrong but you can't expect the same level of service which you are used from Amazon for Marketplace sellers.

Couple times I ordered something without double checking that it is sold and delivered by Amazon and had nothing but trouble. I’m sure there are honest Marketplace sellers as well but I just can’t be bothered.

I hope that the OP gets his money back.