Virgin media are poor

[Walt]

... so if it's your problem, not BT's, what do you expect?

If you're not a telecommunications engineer, how would you know?

[ccs]

BT can usually work out where the problem is over the phone.
If the external wiring has failed, or there's a fault on a substation, they'll know.
If your BT router/modem isn't working they'll suggest things to try, and if it still doesn't work its probably a router hardware fault.
If you're using your own router then it's not their problem.
Not much else can go wrong, as far as BT is concerned.