Useless telecommunications

I'd like to badly review MTN for what they did to me, I had a Data Sim Contract them which was scheduled to expire in July, around June I took a router deal and canceled my data Sim contract and then I paid cancelation fee, fast forwarding four months later they increased my data Sim deal which I never agreed to it and I tried to phone they don't pick up, I tried Sending them a inbox on FB they never follow up. I am so annoyed because they dedicating more and now I am able to plan accordingly with my finances.