Poor service received from Mc donalds in polokwane Savannah

Today at 4:30 I bought food at mc Donald's in polokwane Savannah I swiped using my capitec card,the transaction went through twice and i informed the cashier who told me that the 1st transaction will be reversed however the transaction was never reversed and I went back to mc donalds to inform them and i was told to bring a statement, i dont understand why should i provide my bank statement when i can see that the 2 transactions went off and was never reversed.