Payment does not reflect on my account!

On the 31/12/2014 I made an extra payment into my account of R380.00 over and above my instalment. For the month of December I paid a total of R1488.00 were my instalment was only R500, on Edgars side they only reflect R1108.00, I have the EFT Voucher from the store and my bank statement which reflects the payment made as proof, I have contacted Edgars about 20 times, I have faxed through and emailed the EFT Voucher through yet no-one seems to care to assist me, I am pushed from one department to the other and even contacted the store yet I have had no luck, No-one can tell me were this payment is lying and now I am being made to pay this amount again in my recent statement, I am extremely ****ed off and will not be paying a cent further until this payment is found and allocated to my account, WHY MUST I PAY ANYMORE WHEN PAYMENTS JUST VANISH? Yet if we don't pay we have 50 calls in that month to find out why!!!! So I will not be wasting my time contacting Edcon again, they must contact me if they want any further payments!!!!