Poor customer service

I purchased a mobile phone from Ackermans in Promenade,the drop down icons were not working, battery life would not even last a day and the phonebook wasn't saving any of my contacts...the following weekend I took it in and they took it and said they were sending the phone for repairs,almost 3weeks in I received a call to collect the phone and to my discovery the phone still had the same issue . After standing for almost 2hours they agreed to give me another phone and not of the same model as the one I had purchased was now a R100 more and they wanted me to pay the extra R100 difference for a mistake they had made. They resorted on giving me my money back of which wasn't my request as I needed a new phone not cash back. I took my money and left unsatisfied as I expected them to pay the difference and give me a new phone as acknowledgement that the fault was that of the store and as compensation for the inconvenience.