No discovery miles for fuel spent despite going via call center.

I did not receive my discovery miles for September for petrol purchased at Shel or BP garages. Phoned the call centre a few times. They finally said it would be paid in the next run. Not only did I not receive the promised payment for September, they also did not credit miles for fuel spend for October. What is the purpose of going via the call center who only makes promises and does not resolve issues