Contract Cancellation!

I had a contract with Mtn for the past 2 years or more, and since their recent sagas of high fees and robbing their clients of their data, smses and airtime, i decided to call them and request for my settlement amount, which i then went to an Mtn Shop at Gateway and made a payment and settled my account this was on the 16/02/03, i was advised that payment reflects after 24 hours, i waited and called the next day, when i called i was told that it takes 5 working days just to cancel a contract (pethatic), i kept calling as days went by, till today i cant port my number to another network a competent one, Mtn is delaying, they were very quick to open my contract and debit from my account which i have never defaulted, now i have to wait for god knows how much more just for a stupid number to be migrated to prepaid so i can be free from these *****s, I need external help if anyone is reading this i want to know how to take this up, i have settled my debt and i dont want anything to do with Mtn, as well i want them to update on the credit bearaux that i have settled my account , Mtn service sucks no wonder they were fined for billions :-(