"Original Creditor"
Charter already wrote the account off and sold it (in bulk, with other accounts) to a private debt collector at a reduced rate.
Perhaps you really owed, or perhaps not. Perhaps they let account vegetate only to hit you with exhorbitant back fees. I don't know, but I will tell you how this pyramid of parasitism works.
Debt collectors gamble with these accounts, they're not actually entitled to be paid- meaning if you don't pay the collector, you can't go to jail. They must have your acknowledgement and consent and will try to get it from you unwittingly. They will tempt you with bargains and reduced rates, but you're not entitles to PAY THEM. THEY ALREADY PURCHASED THE 'DEBT'. They're only gambling, because they purchase these accounts en masse and hope someone will pay them in full- but they're not entitled in the least to make good on their invenstment. When so called debtors pay in full, that amount is obviously more than they purchased the account for, so they actually make profits on people that pay in full. Of course not everyone pays at all, and once that collector deems the account not likely to be paid, they bundle it up along with the other unrecoverables and re-sell it wholesale to another debt collector at an even lower rate. The cycle continues almost indefinitely until they can no longer re-sell the debt. It's a gamble all the way down the pyramid. If the 7th or 8th collector, who undoubtedly bought the debt at pennies on the dollar, ever manages to actually secure a full payment, they would be making an enormous profit on that one account.
Basically, the moment Charter Communications wrote off the debt and sold it to a collection agency, they removed themselves from the picture and are made whole. The worst thing you can ever do is admit it's your debt to a collector (they're well trained in scripts to get you to admit it), it's literally like the 5th amendment "anything you say CAN AND WILL be used against you". Any correspondence resets the statue of limitations, not like they respect that anyway.
Bonus: For more Fun bedtime reading, take an interest in FIAT money systems backed by Private Reserve Banks. You'll discover that taking loans backed by your signature is how 'new' money is created, and that on taking those loans, nothing (no actual risk) is assumed by the creditor, as your loan is held against speculation (the future, not existing assets). It's an absolutely fantastic story that everyone should know.