Comcast Comcast is trying to make me make the same payment TWICE! Richmond Virginia

Last March I cancelled my service at one place and established totally new service at the place where I live now. I had a final bill of $117 from my former address I will admit it  did take me a couple months to pay it so it went to collection but I did pay on May 17, 2015. I thought "Cool that's done" because that was the last utility bill from my former address, boy was I mistaken.  Comcast sent the already paid bill to a collection agency, since last May Comcast has tried to collect the same $117 through collection agencies like 4 times and get this every time it's a totally different collection agency. I have documentation that I've already paid which I have faxed to Comcast 3 times. I have my bank statement showing the payment and that the money was taking from my account and the letter from the 1st collection agency stating it was paid in full. I even went to a location Comcast office and had them fax everything also. What's really pissing me off is this crap has hit my credit. Every time I call they keep saying they have no record of my previous calls or that I had already paid. I will be so glad when I can get rid of them. They are a bunch conartists taking advantage of the fact they pretty have the run of cable game in my area. I'm willing to switch to direcTV to get rid of them and I hate satellite.