asked for worldcall and cashier processed telkom

On wednesday i took my mom shopping by the amalinda shoprite centre like i always do every month. My mom requested the cashier to process R50 worldcall however the cashier gave telkom voucher. My mom Only realized the next day when wanting to use the voucher that it is not what was requested. Today we went there to reverse transaction and get the correct voucher as initially requested only to find out by one of the managers (michael fiets) that they do not allow such reversals as its company policy even though it was an error on their side! I then asked to speak to the branch manager and michael went to speak to this Mr Goliath whom did not have the decency to come to us and try to assist he rather sent a message with michael to say that it is company policy and they can not reverse it and give the correct voucher! I can not believe this.....my family and i have been shopping at shoprite for years and this is how we get treated! An error on their side yet they refuse to assist the situation and try and correct it they choose to send us away! I am not pleased with this at all especially due toit being an error on your side shoprite. Its bad for customer service!!!!