Furious customer

Could you please explain to me what does this mean "Grap a bite at ANY Wimpy"? Today I went to Wimpy-Heidelberg and that statement definitely didn't apply. I've tried to redeem the 2 vouchers I've had, for myself and my child and I've made sure to order the meals on the FNB App, only to be told their system shows the voucher can't be redeemed twice and to top it all off, HALF of the 1 meal ordered was deducted instead of the full amount (instead of R123.90, only R61.95 was deducted) and the other meal I had to pay in FULL. Please clarify this, because I'm sure a lot of people are going to understand the above statement as I have that ANY meal on the list will be for free. It cost me now more. I wouldn't have gone to Wimpy if I wasn't mislead by your statement. If I miss understood it, please explain what it means.