Virgin Media - address fraud?

Asking this on behalf of a friend. Recently she got a letter from Virgin Media addressed to some Polish bloke she's never heard of. She has owned the house ten years, so someone must have applied for Virgin Media using her address, either mistakenly or fraudulently.

She considered calling them up, but as she isn't a customer she can't call 150 and so she would have to pay to ring them. She assumed that as broadband has to be physically installed at a house, that it wasn't cause for concern like a credit card etc might be.

Now she has received a bill from them in this person's name. I don't understand how they can have an incorrect address and be sending bills?

I have offered to let her use my mobile to call 150 (I'm with Virgin) and get this sorted. She's heard that customer services are a bit useless with this kind of thing.

Does anyone have any experience of this? Who should she ask to speak to (dept etc)? She is worried that if in the future she wants to get Virgin BB that this could cause a problem.

Incidentally, a few months ago she got sent a V5 from DVLA in someone else's name. She tried to contact DVLA (lol!) and failed unsurprisingly, no further correspondence came for that though, so I assume it was an error and the car owner rectified the address.

Many thanks in advance for any suggestions.