It would be correct to say the community works "on behalf of" giffgaff -- but working "for giffgaff" somewhat implies being one of the staff, which most of us are not.
Incidentally, "real" staff are identified by a title that appears alongside their avatar. Anybody else is just another member.
Hi @daysue16 and welcome.
We have an ideas section called Labs.
If you do a search you will find several ideas wishing to promote a deal with Spotity and other streams.
Take a look and choose a one to support by clicking on the "heart".