Bring back my airtime

If it’s not my airtime disappearing it’s the express service not working. I bought airtime 4 times today due to the fact that I will get back to back texts next thing I’m told I’ve been paying R2 per mb. I will buy data but it will take my airtime instead and only after it will use the data. I didn’t know there was a lapse time after buying data coz this has been happening for a while. I want my airtime back and don’t tell me you checked your system and the charge was correct because it wasn’t. I’m tired of this nonsense