Leaving half way through period

[#1]

My account is due to move to another ISP on the 14th, my billing day is the 29th.
The direct debit will be canceled.
How much and how do I pay for the last 14 days online or are they paid upfront and I get a refund? 

[#2]

You always pay in advanced. You should get a refund BUT...
1) Make sure you tell PlusNet when you have migrated
2) Make it clear in a ticket that you want a refund for the remaining period not yet used.

[#3]

Thank you kindly. 

[#4]

AFAIK you have to leave card details on the account for PN to apply the refund to.

[#5]

A refunds is processed over whatever medium the payment was taken from.
Money laundering rules, see.