Vodacom Upgrades nonesense

Keep getting harassed by Vodacom Upgrades. When I asked them to stop calling me and mark the option as not interested, the say we can't. You are due for an upgrade.

What do you not understand, I do not want a new contract and I do not want a new phone. The contract once completed goes onto a month to month and if you cannot understand that, then please cancel it and I will switch to a prepaid sim somewhere else.

****ing annoying