CenturyLink/Qwest CENTURYLINK continues to charge me modem rental lease fees when i bought one instead and returned theirs to them. Internet

CenturyLink continues to charge me a monthly modem rental lease fee on my bill. I personally purchased a Centurylink modem  it was the exact same model of the one I was leasing from them  I was tired of paying for a leased modem of $9.99 a month  when it was cheaper to purchase one instead . Anyway I called Centurylink to inform them I needed to return their modem to them since I no longer needed theirs , their modem I  was returning was still in excellent condition like new and still had orignial box and installation instructions pamplets and all cords and filters that it came with . The tech on the phone said he would send me the return label  that I needed to put on the original box it came in and then mail it back to them.  I received the return label and  in the box I enclosed a letter explaining why I was returning the modem  and informing them that all contents that it came with was indeed being returned to them in great working condition , I also included my name and account number and billing address  etc  and also mentioned that  I should never see a rental modem lease fee on the bill ever again.

Well low and behold my Centurylink bill still has the modem lease fee included in the charges on my bill. I have contacted them many times on this and they always say it has been taken care of and won't be on the next bill and I will be credited for the charge , but they lie and continue to put the charge on the bill. 

Also the modem I purchased worked great until I called them about the charges of leased modem and then all of a sudden my wifi signal won't stay connected  to the internet , it keeps getting dropped and disconnected for some reason , so I called the internet tech line and they said it looks like there is a problem on the line and they needed to send out a repair tech to fix it and there would  be a charge of $89.00 added to my next bill , that to me is a bullcrap scam if I ever seen one .  

This is not the only problem that I have had with Centurylink either. I have other charges on my bill that should have not been there and sales agents ripping me off with bogus charges of services I never ordered. I am so tired of Centurylink  and their bullcrap.  DO NOT DEAL WITH CENTURYLINK . THEY WILL RIP YOU OFF AND LIE ABOUT IT !