Please help

I bought wors at roots butchery Mam's mall on the 31st of last month, so last night wanted to braai the wors the smell that came on it was bad and when I taste it, the taste was bitter, sour, so today I went to the store to return it they told me they can't exchange or refund me coz there exchange policy says so. I asked them where is the exchange or refund policy written because on the back of the slip there's nothing. They gave me an excuse that also there's loadshedding maybe that's y it taste like that, and I told them that I didn't only buy wors y other meat are not rotten like an Ox liver and Mince. So they told me they can't help me, meaning I've lost. Even tryed calling there customer service they r not answering