Moving house/call barring

[#1]

I'm moving house in two days time and will not be taking my PN service with me (nothing personal, just different availability in the area I'm moving to).
Due to mislaid paperwork, PN have yet to cancel my account.
I'm worried that the new tenant will move in and run up a huge phone bill before PN have cancelled the service.
Is there any way I can request barring on all outgoing calls to prevent this happening? If so, how long does it take to be activated?

[#2]

Never mind, I asked about this as part of an ongoing ticket about another issue.
Both issues now fixed, and £25 cessation charge waived because of all the hassle!
Many thanks plusnet