Got Double Billed for a Second Account After Speed Upgrade

I upgraded my internet speed from the 1gig plan to 2gig, through a rep, and I just realized that this plan upgrade was opened as a second account. I just got charged $90 for the inactive 1gig plan under the old account at the same address, a week after i just paid the $100 for my current active plan. This is ridiculous, I'm clearly just using one service! I need the charge reversed and the old account closed ASAP!!!