Pre booked and paid for seats not given

I traveled with Mango 4 January 2016 from George to OR Tambo.<br> <br> When booking the ticket, I selected a pre-booked seat and paid R55.00 for it. When I checked in and received my Boarding pass, I noted that the seat allocated to me wasn't the one which I had PAID for. No one was willing to help me, staff merely shrugged stating that the plane was fully booked.<br> <br> Mango is the only airline that I've ever flown on (nation and international) which was not able to provide a paid for service of a pre-booked seat after it was paid for.<br> <br> When I went to the Mango counter the lady merely gave me a number to call, stating that Mango might refund me with a voucher.<br> <br> I DO NOT want a voucher as I am not intending to fly with Mango ever again. I want my money back for services paid for that wasn't provided.