!!!WORST SERVICE NETWORK I HAVE EVER USED!!!

I am so disappointed with Cellc right now. If it's not their bad service,it is them chowing my airtime.

So I bought R20 airtime on the 17th of April 2021. I wasn't using it as I use Rain for data and I had free minutes. Today the 21st of April 2021,I check my balance and I see a R0.00 balance. I am surprised and asking myself what might be the problem. So I decided to call one of the call agents and she tells me that I have to set my spend limit for data to R0. So I asked what this means. She further explains even though I have data,I am still using my airtime. It doesn't even make sense because I've had the airtime since the 17th, why only today that my airtime disappears. In the past, I've bought airtime, did not use it for days and it has never disappeared. Why today out of all these other months that I've been using Cellc? I need answers because all of this doesn't make sense..