Expired prawns and mussels

I am a regular customer at Food *****s market Parkmeadows. I had complaints about the chicken before but now its a different complain. Last week i went and bough a big Box of prawns with a pack of Mussels in the Frozen fish section. The day i had to cook it last week I took it out to defrost and i cooked it Friday Night. When i opened the pack of mussels that was defrosted it had a bit of a bad smell. It smeld like Seawater in a bad way. So i thought its normal. I started cooking that and i added the prawns. When everything was cooked up and my friends came over for dinner we started dishing and my one friends started eating hers right away. After the first prawns she said it tastes bad so i thought i didnt cook it well enough so i tasted and there was something wrong with it u could taste that it is old and expires the mussels on the other had was like a explosion in our mouths when we bitted it like sea water in your mouth. So the dinner was a big mess up with the rotten/expired prawns and mussels and had to go get take aways. i get very upset if this happens to me and would like food *****s market to contact me urgently about this problem.