airtime disappearing and call centre drops calls

The other day I bought a daily data bundle I loaded it then I get a sms few hours later to say I got that wow thing but I didn't use over r5 airtime so I check and r5 was off my airtime, but I never phoned anyone and I still had data bundle active, this is not the first time this has happened, you phone the call line and as you get to the option to speak to a operator the call gets dropped on numerous occasions, I'm not subscribed to anything so please explain, where my airtime keeps disappearing to, this is shocking service and once my data bundle expires I'm doing a sim swap tired of being **********