5-year Guaranteed discount taken away

I went into an Xfinity store to add a single additional TV box to my existing bundled account. The agent processed it incorrectly as a full plan change, which completely stripped away my active 5-Year Price Guarantee and caused my internet bill to jump by $65. I need a corporate care agent to manually reinstate my original 5-year locked-in base rate.  There were 45 months left on the "Guarantee".