Poor customer service.

I went to purchase 3 items from Mr Price K90 centre Boksburg on the 3rd of April using my debit card. After the first attempt of entering my pin, the cashier said my card decline. At the second attempt, the transaction took even longer and declined once again. It was only at the third attempt that the transaction was approved (even though i had enough funds in my account for the transaction). An hour later as I arrived home I saw two messages saying my transaction went through twice. I went back on the 5th of April to question it as the money did not reverse in the 24 hrs after the transaction. They said they would reverse it and call the next day. They also said that they were willing to give back cash if it did not reflect. Needless to say I did not receive the money, nor any calls. I went back today, the 13th of April to query it to which i was told the manager never bothered to follow up during the week like she was supposed to! I was then told (again) that they will reflect it and I should receive it by Monday and that i will be getting a call tomorrow (which I find hard to believe). I then asked if I could not just get cash as it is not a huge amount to which i got the response "we can't give you cash as it will interfere with our cash flow". Fine, fair enough. But why tell a customer you will give her cash, when it'll interfere with your cash flow and why keep a customer waiting for a transaction to be reflected when you could rather refund them cash and keep record of that and rather keep the issue within the company.