TFG Vouchers are a ****

I am utterly disgusted by what TFG does. I opened a store account with them last year to build my credit score. I was then sent vouchers I can redeem for my purchases as a first time account holder. To my surprise non of those vouchers worked. I tried on other TFG stores at different locations. There was always something wrong with the voucher "technical glitch" as they called it. This is **********. Today I got a voucher for my birthday from them and I decided not to waste time and use it. I went to @Home Melrose Arch and bought a body lotion when I tried to redeem the voucher (R35.00) I was told there was a price change on the product and I should spend another R35.00 to qualify to redeem the voucher, that is where I lost it. I asked them to call the manager for an expalanation.