promising **** rewards

Ackerman's says with their new rewards system you can get 40 rand back for spending 500 in their establishments. So I did just that spent almost 16000 rand and got nothing back called their call center and was told I don't qualify for cash back but they wer happy to take my money with the promise of earning stars. Only after I called they sent me 60 rand cash back which doesn't make sense to me. I feel cheated and very upset when I'm such a loyal customer. As I have 3 sons and one on the way...