Paying double for what I want

On Saturday 5 September at about 13:00 I went to buy KFC for me and my wife. The food was fine but when I paid the payment went off double as two different pay points was used when one was freezing up. Initially I asked the cashier what now and she said it would reverse but to date it has not been done. I am very disappointed with this as when I told her what if it does not reverse she told me that I will reverse, now I am not happy with that as I must now use my fuel to drive up and down to get my money back that was wrongly deducted from my account. I am sure this is not how normal people do business, it might not be a lot of money to you as a big company but that money makes a difference in my budget!!