Earthlink Earthlink refuses to send promised rebate on router that I bought from them upon upgrading service. Internet, Internet

Four months ago I upgraded my Earthlink service from just regular DSL to DSL with Home Networking.  Part of the deal was that I would buy a router from the ISP and they would give me a rebate.  A few weeks after making the order and witht the router not arriving I contacted Earthlink via their Chat service.  They told me that I had never made the order.  So I ordered the router again.  Meanwhile, according to my credit card statement, I could see that Earthink was already charging me for the service that I could not use because they had not sent me the equipment that I needed to use the servive.  The router finall arrived.  Earthlink had advertised online when I made the original order, and still now 4 months later, that one could get a full rebate on the router.  Something like $79.95.  I sent in all the required paper work for the rebate.  Then I got a notice saying that my equipment did not qualify for a rebate and to sign this form and send it back.  I did so.  Then I got on Chat service and they told me that thet were straightening the problem out and I would get the rebate.  No rebate came.  I got another form saying that the equipment did not qualify.  I got on Chat again and they asked that I fill out the application "one more time" and send it in.  I did.  No rebate came.  I just got off the phone with somebody in India, I think, who assures me that my rebate will be coming in about 6 weeks.  I doubt that this will happen. 

 It is now June 2012.  I have been wasting my time on this since February.  Not a good company but it is a pain to change ISPs.  They will keep charging you on your credit card soemtimes until you get credit card company to shut them off.  ISPs are notorious for this.