Invalid vouchers, and no response after reporting this a month ago!

This company is a bunch of ******! I did an upgrade through them, and they were running a promotion whereby you get vouchers when you do an upgrade. I received 4x R100 pick and pay vouchers, but two of the vouchers were invalid. I have reported the matter with them a month ago, and have been making follow up phone calls with no success. All I get told is that it has been escaled, but they won't let me speak to a supervisor or manager. I have sent plenty emails, and no one responds. They are ******!! I want them to cancel my upgrade now, I don't want it anymore!!!! Absolutely shocking that you report a matter, and a month later you still don't get anyone calling you back. I have wasted too much of my airtime phoning them, and they never call back. Absolutely shocking and disgusting!!