Unauthorised increase in set contract fee

I "signed" a contract for a set amount for a 3 year period in Nov 2025 and just received a message about a price increase happening Feb / Mar (the when is irrelevant as I was under the impression the amount was set for the 3 year period). Never in all my years of contracts with another provider have I had a price change occur in the duration of a fixed term contract. Attempting to contact them was another story altogether: I phoned and was given 2 options - New / cancellation of contracts or general enquiries. Selecting General enquiries takes you to a bot which asks 3 questions and if those are not the general enquiries you had you are out of luck as the next sentence is "Thank you, Goodbye"...not helpful. I need to speak to a person so to this end I tried again and selected the option for new / cancelled contracts. They informed me there is an increase every year, but I informed them there was no mention of it when I took out the contract. They gave me another number to try. I duly did so and was met with the same options as the previous number (which falsly identifies itself as customer "care"). Finally arriving at a person I mentioned that I did not recall agreeing to a price increase and would like them to play that part of my call for me and I was informed that it would have to be requested. I was told that if the operator who signed my contract with me did not mention the price increase then it is because they were not aware of it as Vodacom only just informed them (shocking as I thought that I was talking to Vodacom). I was told I should take it up with head office. They could not escalate my call to someone who could help, they could not give me contact details for head office and most baffling of all suggested that I put it on Hello Peter if I want a response which does not feel like a great business model to me, but ok.

So I would like to speak to an actual person who can assist me to sort out this situation. Ranting on social media not my usual go to, but this has not been a good experience so here we are.