Correct cancellation date?

[#1]

Plusnet have acknowledged my intention to leave on the 16/06.
My new supplier took over the line on the 30/06 and my cancellation date for Plusnet is now 07/07.
Is this correct and standard policy is it normally a week after activation?
I would have thought the plusnet service would stop on the 30/06 as I am now paying two suppliers for the same service.
Thanks
Chris

[#2]

I can't answer the specific point but in general an account isn't closed until a few days after the move to pick up any phone charges as they don't come through immediately
The charges for line rental and broadband should stop on the day you leave with a pro-rata refund for the remainder of the billing month