Apologies for the issue and the experience that you described above.
Looks like the promotional and discounted contract pricing on your Internet Plus Basic package ended. You were enjoying a discount of $28.96 a month on this package as per the agreement.
That $28.96 variance plus some associated and corresponding taxes, fees and other charges (due to the new higher monthly rate) resulted in an additional 83 cents this month for an all-in increase of $29.79 month over month.
I hope that helps to explain.