How do you know BT have not received it?
If it is because you have received an email from BT, these emails are automatically sent out until such times as the account has been updated to say that the kit has been returned.
It is presently taking BT up to four weeks to update accounts after they have received returned kit. As you only sent it on the 3rd or was it the 4th there is still plenty time for your account to be updated.
If you had the Proof of Postage you could have called BT 0800.800.150 and they would have updated it for you.
