C6300 needs RMA but support wants money to do it

So my C6300 recently stopped running at speeds that it used too.  I typically get around 137 - 150 Mbps.  As of about 2 weeks ago it started capping around 65 - 80.  So I have had Comcast out to the house, they replaced all the wires, ran tests on all the lines, and everything looks good.  I have factory reset the router more than once and power cycled more times than I can count. But the speeds remain the same with the C6300.  The WiFi off the C6300 is even worse, that caps around 15 Mbps.  Now, the frustrating part about the entire thing is that Netgear wants me to pay them for them to "diagnose" the hardware problem to replace it.

To me this seems like something that Netgear should just handle and I shouldn't have to pay to have it fixed.  This is a terrible way to treat a customer that paid a couple hundred dollars for a product.  I expect it to work longer than 6 months.