As you are buying out you won't be using the services anyway so you may as well PAC your number over to your new network, or take your new contract immediately.
Once the final bill is paid you can cancel the DD but make sure you check with CS that the account is closed before you do.
I have no affiliation whatsoever with O2 or any subsidiary companies. Comments posted are entirely of my own opinion. This is not Customer Service so we are unable to help with account specific issues.
Please select the post that helped you best and mark as the solution. This helps other members in resolving their issues faster. Thank you.