Telkom is overcharging me

I have took two cellphones with Telkom November 2022 with the agreement that I will be paying R1700 plus sim only for 40gig data, January they send me the statement that I will be paying R1800 from February it has increased now I'm paying R2200 when I go to the store to ask what is it for they all says they don't know , they will lodge a call for head office to call me. Till today I have not received their call and my money back.