Thumb Sucking Tendancies - Breech of Verbal Contract

I have had enough with the bull**** service that i get from Vodacom, everytime i contact them they give me a different cancellation date. i clearly spoke to a lady last week and her advise to me was "sir just call on the 27/12/2017 and you can cancel your contact on the same day and it will be cancelled, i asked if she was sure and she said yes with no hesitation". i called today and the guy told me that the contract can only be cancelled in January 2018. and this isn't the first time they are doing this. Where are the guys thumb sucking these dates from???? must no1 ever cancel a contract with you guys???? i only call Vodacom from work now because my calls are recorded because i cant trust them anymore. The lady gave me a verbal agreement that the contract will be cancelled today and i want this to be honored. Listen to your calls with your clients and tell me that i am lying and i will play the recording to you!!!!!!!!!!!! i still have 2 other contracts with you guys, if Vodacom can do this to me and i am with them for over 15 years, IMAGINE WHAT THEY CAN DO TO YOU!