billed account but no data

I am billed every month on the 15th and usually receive my data same day. Month of september i was billed but received no data, so since it was late i purchased my own on the 16th. Now that i am enquiring about the data that is not received they say they sent it on the 16th but it cant be because that is the data i purchased myself. I am given the run around by the call centre reps that are unwilling to help and now even the shop assistants are not even willing to do anything telling me if 808 couldnt help they cant too. I am disgusted that i have to accept the fact that mtn did billed me for something i didnt get, that is broad day light *******. I am disgusted by their service and highly disappointed.