Mistake in converting from Residential-Business, now in collections?

Hello, 

HELP:

I am not sure where to turn for this as we thought we had resolve in November of 2014.

Back story:

We converted a residential account to a business account in August of 2014

The residential account was supposed to be turned off.

We paid the business bill appropriately every month and are still paying. using it.

November of 2014 we get a bill for $200+ for the residential account which was NOT turned off, mistake by comcast.

November of 2014, I worked through the comcast process about 3 times spending around 4 hours talking to around 6 different people. All was resolved, or so i thought.

I just received a call from ERC debt collections of Jacksonville hired by Comcast for 200+ dollars for the residential account! They were adamant that i owed the money, they didnt buy the debt but hired by  and Comcast wanted the money. They asked for a receipt showing the debt was cleared. Of course i didnt get any paperwork from comcast.

PLEASE help me. Call me direclty on my account number, email me directly or something. 

Who can i call directly that will get this resolved.