My CM400 is locked to IPv6 by Spectrum; can't connect to WOW internet

Spectrum downloaded a firmware update to my CM400 cable modem and now I can't connect to WOW Internet after I switched my service to them. Is there any way to load a new firmware version to unlock IPv6 so I can connect to WOW? I'm not a happy Netgear customer right now because I bought the CM400 before I subscribed to Spectrum and am now locked out of WOW. Surely Netgear has a way to fix this? Please help!!