Newer modem won't work with slower service plan? This sounds fishy.

Hi,

I have older service plans (“Cox Internet Preferred” (250/10) and “Cox Advanced TV Premier”).  I have a personally owned Motorola/Arris SB6141, which is DOCSIS 3.0, and on the Cox list of certified modems.   I get about 170 mbs download speed according to Speedtest.net.   I bought an Arris SB8200 (DOCSIS 3.1, and also Cox certified) hoping I might get closer to the 250 mbs rating and also to have a DOC 3.1 modem in place for when I decide on future service upgrades.

When I went to activate the new modem (SB8200) I was not allowed to use the self activation.  I got this message:
“Error:  Oops! You do not have access to the Self-Activation experience because you do not have an open order that requires device activation. If you believe you've received this message in error, please contact us.”

I called customer support and I am told that the new modem will not work with my current service because my current service is too slow.  I am told I need to update to a 500mps internet + Contour Ultimate package for the new modem to work properly (which also requires a $100 “pro installation”).’  I declined the service plan "upgrade" and I am using my old modem as before (with my new modem sitting around unused).

This sounds like a bunch of B.S.  Every source that I consult (such as Arris and Netgear websites) says DOCSIS 3.1 modems are fully backward compatible with DOCSIS 3.0.  It seems like the activation restriction put in place by Cox is solely to make people call support and get the hard-sell to a new service package/plan.  

Looking for some real information about why I can't use a new DOCSIS 3.1 modem with my current service plan.  I’m a 15+ year customer and not happy.  At all.

Thanks,
Dean