MacJ's Food Wholesalers Chickens

I Bought 20 chickens from MacJ's Wholesalers in Brakpan on the 13th of March 2020 , Box/packaging had use by date of today the 16th of March 2020 when i wanted to braai the chickens on Saturday 14th of March 2020 they were already off (bad smell) so I couldn't sale those chickens.I Phoned them to ask if they can replace these chickens as I can not serve rotten chickens I was told that it was my fault as I didn't look after the chickens, how unfair is this these chickens where in the deep freezer since day i purchased them a day later they were rotten