Can't exchange insured decoder.

I exchanged the HD decoder for another at the Rustenburg DSTV agency shop. They said they tested it and it was working. I bring it back 150kms and find that most channels had a E16 error. It tried all night to reset it without success. I was even told to get a technician to realign the dish! So I have to go back to shop at great cost please give me credit or I will cancel subscription. This is trash.