Disappointment from day 1

I signed up for a fibre line. Installed 30 August, contract starting 1 September. I've asked to test the 25/25 speed, and if not sufficient, change my contract from INCEPTION 1 SEPTEMBER 2023 to a 50/50. I am now billed an upgrade monthly fee and not sign up. That is not treating customers fairly. I've raised it with the email centre, and never received feedback after I was promoted the call will be listened to, as I was never advised of the monthly charge change