Sheet Street not crediting customers bank accounts

I had purchased a few suction holders to use in my house, within 5 minutes of hanging them up they fell down. I returned the items to the shop of the 26th April, when my card was apparently credited over a week later my account still has not been credited. I have made several calls where when people cannot assist me they just cut the call or they transfer me to another department who has no idea what is going on. I have sent messages on Facebook, emailed and called the actual branch and no one can help me.