"We had naked VDSL with Snap but it was erratic and we couldn't depend on it for making emergency calls with VOIP. So we asked Snap for a POTS based telephone service but they refused to supply this because of our high needs requirement due to a medical condition. I think this is discrimination and are they allowed to do this?"
Personally I expect there was some mis-communication on both ends and doubt any ISP would ever say this. But if they did, I'd certainly want to complain about it regardless of whether the ISP could legally deny a request for service.