Billed out of bundle

I took out an additional contract in Dec 2016 and received 30gig promo data.<br> Bill for Jan showed that I owed R 1278.02 on that new line for data usage.<br> I have spoken to more than 6 MTN consultants querying how come since I had 30gig, and all of them were taking up my query to billing department for further investigation as it did not make sense to them as well.<br> After 3 months of querying,(no one ever came back to me, I had to call for follow ups all the time), I receive feedback today that I was correctly billed as activation takes 2 -24 hours (first time hearing that) the consultant selling me the contract never told me that.<br> MTN is robbing me blind, they have a nerve, they took back 25gig of that promo as it had expired and yet want me to pay for 1 gig that I used. Why can that 1gig not be set off from the 25gig?<br> How does MTN justify that, you lure a customer with a free 30gig , you don't explain the technicalities of activation, you take back more than 80% of that data and still charge the customer ? Really?<br>