Bad Service

Baby Boom has bad customer service. My sister received a baby car seat as a gift which was bought at a baby boom in Mthatha and she had already bought one that was a set with a car pram and all... Immediately I returned the car seat at the baby boom in East London and I was told they don't do exchanges and refunds on car seats even though it was still new on its original packaging, they even have a sign on the wall. I then contacted baby boom on Facebook requesting that they do an exchange for something else as we cannot have 2 car seats. since August 2018 I have been trying to get them to do the exchange but they keep saying they will get back to me and its clear they wont. What are we supposed to do with the 2nd car seat? when we could be getting something we don't have with that amount?