dissapointed

I did a lay bye with ackermans in Cresta store and collected the goods .when i got home the other of the shoes had a missing string and the other one was torn as it was squashed from wherever it was being kept.it was unfortunate that i had lost my original receipt but i had the lay bye slip so they could track the purchases.i had bought one of the shoes for 79 rand and in the system it was now showing 59.00 and they said they wont refund my 20 rand as it was not their fault that i had lost the receipt.The manager was very rude and not helpful.Kindness goes a long way even if its a 20rand.