Mtn deduct 5.6 gig from my internet bundle.

On the 10/4/2015 i bought 10gig bundle from mtn and received 5.6gig free which expires within 15 days in total i had 15.6gig. I used the 5.6gig within 15 days but yesterday i received a message that 5gig had expired and it seems like mtn took another 5.6gig from my remaining balanced that i had of which expires after 60days from date of purchase. And according to their T's and C's 7.1 The giveback bundle and value shall be depleted first and in my case i already used it before the 15 days and i find it unfair of them to take back that 5gig from my remaining bundles which was 7gig yesterday and today i was left with 1.4gig. I demand that my bundles be replaced since i comp**** with the t's and c's. And this is the 3rd time it happens to me, i raised it last month and i had the phone dropped a couple of times by call takers and i let it slight but now it is happening again and i think its only fair to say mtn is *****ing from me. I hope that there is someone who can help me with my complain cause it seems even the operators dont know their own product cause when i explained to the lady my problem, i was told that i was billed on my 10gig first. My email is [Email Removed]