Look at the wording of your contract. Maybe, on a two-year contract, there is an increase after the first year.
No, it's a 2 year contract which is not even into the 2nd year yet. However, I did contact Comcast and they stated that all of the increases were taxes. Always, something.
If you compare this bill to last month's bill you can see what changed. If you did not go off special pricing period (not the contract period length), the cost moves to regular price.
Taxes, fees, can change any time.
This is the same for any utility company. You stop paying and you may lose service and will owe late fees.