Similar problem with Virgin. I sent info on 29th Jan, week later said they needed more... week later still more... week later submitted last bit and success! I read somewhere if it fails too many times you can start again with a new claim before end of Feb.
The delivery note that came with the phone and 'complete new contract' dated email combined with e signed document dated. sorted in the end.
You need Date, device name, supplier branding etc all on one page.
Hope you get it sorted, took 3 weeks for me.