New router I didn't ask for. Should I be worried?

Virgin Media (bless 'um) have sent me a new router "Because you have both Virgin Media broadband and an O2 mobile plan, you’re now eligible for exclusive Volt benefits." The problem is that I haven't got an O2 mobile plan. (I was trying to sign up for an O2 account so that I could use the wifi in the coffee shop, but I'm not sure if if actually got one.)

The second problem is that there are dire warnings that if I don't install the new router within 5 days that I will lose my  service.

What to do? (apart from wasting half a day talking to VM.)

Thanks for any advice.