I know a similar offer was posted a while ago but it expired and didn't have £50 cashback!!
I have used e2save 4 times on cashback deals and all went through fine. I even have a e2save cashback contract at the moment.
NEC E540 12 months FREE (12 month contract), not sureo n the contract details but free is free. £50 cashback with quidco. Even if you don't have a quidco account you will get £45 cashback.