Telkom mobile saying I don't have data just after loading data

After buying my monthly LTE data, it worked for few days and then it said my data is finish. I loaded more data but it still said I don't data. Thinking I bought the incorrect data, I then changed my tariff but I still had the same problem. Now I have spent more than my monthly budget on data and I can't afford to by more. I can't change the tariff back to the one that uses the data I have loaded. Customer care said there is nothing they can do for me, I must just wait for next month so I can change my tariff back. It doesn't make sense that Telkom mobile cannot reverse this change. and they can't explain why I'm getting a message that I don't have data. This is frustrating