Unsatisfied mtn customer

If I could I would attach my till slip, I have a promblem with what happened today I went for a Sim swap and I was charged 50 but when I look at the slip it says airtime purchase R11 and my change is R39 but I never got my change back the person who was assisting me Sipho from mtn shop south gate, couldn't explain the receipt or till slip they gave to me. I requested to speak to their store manager and I got excuses about her being on lunch I waited for 30 mins but there was still no manager to speak to. I then asked them to put me through to the call center or head office so I can confirm what was happening, they said they were offline and couldn't connect me. My sister did a Sim swap at mtn midrand two months back and was only charged R1 for Sim card. I would understand if the till slip I got was written R50 total for sim swap but I'm still puzzled that it said airtime and change that they couldn't give to me. Mtn South Gate outlets are ****** and ********** I didn't mind paying but at least give me proper proof of payment not the nonsense they gave me. I'm really disappointed at Mtn South gate and Mtn as a whole for letting such things happen with being scrutinized after all we your clients for more 10 years at that. Regards: unsatisfied customer