Rate increase??

I recently got a letter from Xfinity stating my rates will be going up from Jan 1st because I have been paying promotional rates. However I have been paying regular rate of $45 per month for 25Mbs service since Jan 2019. My promotion ended end of 2018 itself. 

I do not understand why you think I am on promotion and why should I be charged more. You will leave me with no option but to to look for alternatives. 

Jay