Payment not allocated by the store but is reflecting on my bank statement.

My mother made a payment at Foschin store in Circus Triangle Umtata Eastern Cape on the 9th of February then electricity went off and I didn't get the slip, then on the 10th February it appeared on my bank that the payment went through. On the 2nd of March I went to pay and also enquire when I saw the balance that the R1000 didn't show, they didn't minus on the account at the store. The lady at the store called their head office and I was told the money went through. Then on the 4th of April when I went to make my monthly payment , it still didn't show. The balance was still not showing, they told to bring the confirmation letter from the bank. I came with my bank statement , then they still said they want a reference number and proof of payment. Even though I had my bank statement,.the bank says there's no other proof except for the bank statement. The money that went to Foschin is showing on the bank statement with the reference so I don't know what more do they want as the reference is on the bank statement.