Delphi didn’t do anything wrong
Delphi’s return policy clearly states returns must be made within 30 days: http://www.delphiglass.com/page/main_returns
I’ve ordered from Delphi several times and have had nothing but good experiences. I even received a broken slumping mold in the mail (mishandled by carrier), and when I told them about it, they immediately sent me a new one free. As a consumer, it’s important to educate yourself on a vendor’s policies prior to making any purchases so you know what to expect.
As far as the performance of the fusing mold, did you follow any firing instructions or look on resource pages like what Bullseye glass offers for free to get guidance on what temperature to fire to? Texture and casting molds have to be fired much higher than slumping molds to get the desired effect.