they most definately can stop you using a VPN, and do. the ones bannign usage are the ones you dont need a vpn for, its not for referrals as they dont really want you to use one/. its people sharing accounts / selling streams on / restreaming on kodi etc that they are worried about
when i renewed my last sub they forgot to renew my vpn access and my streams went black until i got them to whitelist my vpn servers.
bbc iplayer / netflix / real-debrid all block vpn access as a routine [debrid allow you to whitelist on request, but wont allow you to use a private server]