Bad customer service

I bought a decoder at Pep Stores in Sterkspruit on the 6th of August and when I try to install it , it didn't come up and when I try to return it to the store the manager told me they need to contact someone to check it and they will phone me and apparently it's open. I don't know what was I supposed to do. Not open it? Can I please get my money back from Pep Stores? I don't even want that decoder anymore cause of the attitude I got from the store manager.