Frustrated customer

I paid my account online and the amount remained uncleared, the shop needed to authorize this from their side and failed to and as a result my account accumulated arrears. After a long back and forth conversation between me and the shop reversal of the amount was done and I had to repay at the shop as I no longer trust their online payment system anymore. I am frustrated that I am told I still need to pay for arrears that accumulated even though it was an error from their side.