Mtn upgraded my contracts without my consent

I need assistance from mtn had called 3 times already.i have 3 contract phones with mtn of wich 1 was suppose to be done last month.i see on my tax invoice that 2 of my contract phones that i took out in 2019 contracts dates state that i took them out this year in january and will end 2024 i had told them that i did not give them consent to upgrade my contracts and i most defnitly did not sighn anything.are anyone expiriencing this problem?