Bad service

On Friday 12 June 2015, I took a few items on my account. Received a R25,00 voucher if you buy for R250 or more. I returned some of the items today and upon looking at my credit note I realised that the pants were R379,00 but my outstanding balance is R380,13. I phoned the shop to enquired about this and also asked about the R25,00 off of my purchase. The lady that answered the phone was very uncooperative. She did not want to help me over the phone and said that she would phone me back after looking at the slips. I phoned again but was then told that they tried phoning me but my phone was off, this is a lie, but they cannot help me now because they are very busy. I rep**** that I was on the phone now just tell me what they \phoned"me about"