Is it possible to change my payment dates
For TV passes it is possible as I had mines changed when I joined years ago. Best option is to fill in a form detailing what you would like.
As for broadband, I certainly can't see it being an issue if you use the free-from number on the link below.
Whilst I appreciate these are "complaints" forms, it is the only way to get in touch due to Live chat being down thanks to COVID