Vodacom contractual clauses

My premium has been increased without any prior notification whatsoever, they conveniently say its in the contractual clause , I and everyone that queried this today had no idea of this particular clause that Vodacom can change things on the contract as they deem ....what's the use of sighning a contract if things can be changed without clear notification of this....Vodacom stated that they sent a increase notification on the 9th of Feb 2022, I recieved no Vodacom notification on the 9th of Feb. I WILL NOT RECOMMEND VODACOM TO ANYONE BECAUSE OF THIS CLAUSE IN THE CONTRACT THAT STATES :VODACOM CAN AT ANY TIME INCREASE A PREMIUM OR BRING CHANGE TO A CONTRACT AS THEY DEEM, AFTER THE CLIENT HAS SIGHNED A LEGAL CONTRACT . I WILL NOT RECOMMEND VODACOM BECAUSE OF THE UNDERHANDED MANNER THEY STRUCTURE THEIR CONTRACTS.