Conversion of Allocated Airtime to Bundles

I have been with the cell c network since 2007 and recently after my contract upgrade a year ago, I have been allocated with R100 of airtime monthly, however this airtime cannot be converted to any of the bundles not even data... this is silly and stupid as if I need to use the internet or any social media applications the I am being charged out of bundle rates which is almost R2 a mb, this is ****************. I have contacted your call centre in which staff are *********** and their response is " Sorry cell c does not allow you to convert your airtime but you can still use the services and be billed out of bundle rates". Other networks which do allocate you airtime does allow one to convert the allocated airtime to bundles so WHY is CELL C not allowing is users to do so?

I would really like a response ASAP and someone who could explain to me as to WHY CELL C Does this.

Thank you.... One Annoyed Customer