My money gone for good

On Sunday i went to Joshua Doore to pay my Russels account, two days later Russells calls me to tell me that they did not receive my payment when i call Joshua Doore the cashier says she does not remember anyone making a payment of R6350 on Sunday the 12th April 2015. So now who must pay Russells that R6350 ? Is it me again? I am beyond angry because i did not get the money falling on a tree. Someone needs to give me a good explanation.