If you cancel a Plusnet FTTC connection (not migrating / complete cancel including phone line) and you are *not* in contract do Openreach charge Plusnet a termination/cessation/disconnection charge?
OpenReach has no visibility of the contractual relationship between Plusnet and their customer.
When you take an 18 or 24 month contract with Plusnet, Plusnet are *not* taking an 18 or 24 month contract with Openreach.
The Openreach
price list is public information. In the case of SOGEA, the service cessation charge is zero. I haven't checked the old-style WBC + FTTC arrangements.
However, when you cease a service, some ISPs do charge their customers a cease fee (if they're not migrating away to another provider). You'll have to check your contract terms with Plusnet to see if they will or not. Whether or not Openreach charge a fee to Plusnet is irrelevant here; it's the contract terms between Plusnet and the customer that matter.