Poor service

I'm very displeased with the service at the Mr Price, my issue is as follows: 16/04/2018 I made a purchase for the amount of R369.95, however I was double charged. And up till now still not have credited my account. The following day they requested I come with my bank statement and consulted with manager in charge. He signed my bank statement and informed me to wait for 3 days for my account to be credited. However it wasn't credited. I then went back to the branch to check whats happening and went with another copy of my bank statement to the branch and spoke to a different manager in charge. She gave me a totally different story. Their service is really pathetic and would like my money credited back to me because I did present proof of them double charging me. Up till now they haven't even called me to inform me how far they are with regards to solving my issue. This unprofessional.