Dialing free to mtn customer care number not free

I had an issue today with my data. I called 808 from my mtn number. Waited 5 minutes for an answer just to get transferred to a different department and had to hold for an operator again for about 10 minutes. He didn't really know what he was doing and i got a warning from my phone that the airtime is almost finished. I asked him if this call uses airtime and he said no it doesn't but thats not his job, i mist contact billing if there's a problem. Quite rude. Next thing I know, the call was ended as my airtime was finished. Now i was sitting with 2 problems, because I tried to fix one. That's how mtn works? I phone again from my other phone and got told that the will investigate why it happened. Luckily a nice guy answered and fixed the data problem, no I'm just stuck without airtime. Haven't heard a word or received a cent back...