Yellow bucks ****

I'm having a problem with this mtn Yellow bucks reward program and this not the first time.

Yesterday I cashed in 2 x R50 McDonald's vouchers on the app which was 2900 points. I went into McDonald's to buy and redeem then it kept getting declined I tried on the Uber eats app and it said voucher invalid so today I tired again with a R25 voucher which was 700 points and it gave me the same message in the store and on the app now I look like a stuip fool in that McDonald's and now 3600 points is gone and it takes me 14 minutes to get hold of customer care service 135.

I own 2 data contracts by them which are in routers now I must use my Vodacom number to call there customer care service which is now costing me money I'm really ****ed off with this service I'm getting