Prepaid cards

I bought a sealed prepaid voucher on the 09/10/2017 and could not load the voucher and finally blocked my phone. the following day I tried loading it and I still could not load and before it blocked my phone I called the MTN call center for help. The lady that I spoke to told me that the pin was faulty with one digit and that she would help me and load the voucher on my phone for me and this was on the 10/10/17 around 15h18 and the call lasted 5m22s. Around 20h16 same day I called MTN call center again (173) and I was told by their service champion that the airtime was used on a different number around 15H23 the same day. I was advised to go back to the store I bought the voucher and ask for my refund which was odd because the voucher seemed to be used just after I called MTN call centre and the lady promising she will load the voucher, also I was informed that the MTN call centre is not allowed to do that. Finally the agent said a supervisor will call me after investigating my matter in about 24hours. No one call me and I called again on the 12/10/17 at 21h57 and I spoke to a supervisor that I related my story to and he said too that he will investigate my claims and come back to me with in 24hours. Yesterday (26/10/17) called MTN Call Centre again after not receiving any call from them and i spoke to yet again another champion who told me that this is not an MTN issue and I should take it up with the store where I bought the voucher. My issues are this: The voucher was bought sealed The voucher was not used until I called MTN I have been calling them without them sticking to their promise to call me Clearly there is no investigation done on this issue, for the R10 voucher! (Amount to little for their precious time?) i told them I still have the voucher with their SAG number which is SAG7TK7LXG5Y. They could not even promise to refund me...cos thats all I wanted everything else they could deal with in the background Now i want much much more, they should be exposed