billing me for service i dont use

i sent the request the 28 of November to change the degrade the package to THE R250 one the sent a confirmation the the changes will be done the 1st of December on the billing day I'm surprise the billed me R449, I sent the request to query this how ever the consultant addressing the matter seemed to be programed. I ended up informing the service consultant to cancel the sim card I see you continue billing me for something i don't use why is that , since the second of December 2020 not using you sim. i do have proof of communication