Discovery miles not what promised

It happens many times that my spend on healthy food and care does nor correlate to my miles cashback. My Woolworths and Dischem cashback percentage is basically 50% each, every month. For example, my Woolworths spend was about R3000 of which 80% healthy food, got R500 cash back miles, expected at least a R1000. My Dischem spend was more than R2000 and receive nothing in cash back. I've logged 2 queries, no response received. MailRef#***#- and MailRef#***#-. It seems to be a frequent issue many clients have, is Discovery dishonest or ***********? Probably both.