AVIS EBUCKS BOGUS DISCOUNT

I should have read reviews before hiring with AVIS (Budget). What a disappointment. Received a vehicle that was R80 short of fuel. Filled up just before returning the car and they still invoiced me another R294 for fuel. Hardly used the car. I have a feeling they add costs because of the discount through the FNB app (e-bucks). So what is the point of receiving E-bucks rewards if you don't benefit? Contacted customer services, they have no power, tell you to send email. No response. AVIS - please refund me with the R294 you deducted and a further R80 since the car was not full in the first place.