Being charged for plan change I didn't make,given the runaround by chat agents with no solution

I got the 2 Gigabit Internet Plan on March 08, 2026, which includes a $30 discount that expires March 09, 2031 and I'm on autopay which has a $10 discount, and my total has always been $100.90, now my upcoming charges says my charges are $280.90 another chat agent says I ordered a new plan on May 10, 2026 which is not true, I never made any changes to my plan or my account, there must have been a technical glitch but I'm very upset that I'm being charged for a change I did not make. Contact support chat and was tossed around to 4 different chat agents that claimed they would help and I wouldn't be punished for a change I didn't make. But instead kept trying to upsell me things I didn't want and they kept resting my new charge is $140 due to a plan change that was made May 10, 2026 which I kept repeating I didn't make any change or order a new plan and kept going back in forth in a loop repeating the same thing and nothing, the chat agents either don't understand English that well or won't admit their website or app had a glitch that made this change to my plan in my account