Increase in rate despite being on contract. Please DM. Thanks!

Hi,

I am on a 2-year contract for my Xfinity Internet Service. At the time of signup, I was under the impression that the quoted total monthly price would not change for those two years. However, there is an increase in the rate on the current bill, though I am still within the 2 years of the contract. On looking at the itemization, it appears that the credit for paperless billing has reduced from $5 to $2.

Please let me know what needs to be done so I continue paying the total promotional rate for the rest of the contract period. Thanks!