I've done exactly the same, your bill is paid upfront and in advance.
I'd cancel the direct debit as BT take money and add items to your bill without consent, hence why I cancelled my package.
Agreed to stay for £26 a month all included but only got charged this for 1 month. They added on call charges and kept charging for BT Sport when it was meant to be in the package. BT agreed to ban the popular premium numbers for free but started charging £5 a month straight away. BT Sport would also be charged and I'd have to ring up nearly every month to claim it back.
Never again would I use BT, possibly the worst cmpany I've ever dealt with and glad to be leaving.