What's the use of a contract???

I upgraded my cell phone contract on the 3rd of January 2025. I have not even made one instalment, but received a SMS today that my premium is increasing!!!! What is the use of a 24 month contract if it's only beneficial to one of the 2 parties involved. I can not get out of the 24 month contract without paying a hefty penalty, but Vodacom can increase the premium as they wish without being penalised. I've been a loyal customer for many years, but this is now really getting ridiculous. Previously the contract set the period and the contract period for both parties, but the last couple of years the client is forever on the losing side! No wonder majority of the ratings on here are 1 star ratings. Shame on you, Vodacom!!!