Hi BT,
I am having the same issue.
I have returned the kit in July 2024 and have been emailed 5 September 2024 stating I will be charged £63 for an unreturned kit.
Mod - Edited to remove tracking number
as you have tracking number phone CS 03301234150 and they will update you account or try 'message us' at billing
https://www.bt.com/help/contact-bt/account-and-billing/broadband