Cancellation made impossible

I’ve had my Vodacom contract for the full 2 years, I’m attempting to cancel - but it’s near impossible. I’ve sent numerous emails and receive either no response or automated messages. I’ve requested numerous callbacks on the Chatbot to no avail. I’ve been getting persistent calls and SMSes requesting that I upgrade. When on call (this happened again today), I request the agent to cancel, this agent alleged that I would lose my contract number if I cancel (mind you I was using the number prior to starting the contract) they allege they don’t have authorization to cancel - I tell them to request a call back from the relevant department. Instead of doing that, they hang up. I’m living abroad, this very same Vodacom doesn’t allow me to make calls, but I am able to receive them. Cancelling a phone contract should not be this difficult.