We get this problem with quite a few other companies too, not only VM. I think it's also because I'm the only name on the account. This came about because when we set up various insurance and service accounts on moving into the house 20yrs ago, the wife wasn't working, so it was easier to set up everything in my name, and we've done the same thing ever since (apart from Bank accounts!)
So we get calls that go:
Wife: Hello?
Caller: Could I speak to Mr Melter, please?
W: He's at work, can I help? I'm Mrs Melter.
C: Well, I really need to speak to Mr Melter.
W: As I said, he's at work. Tell me what you want and I'll get him to ring you back.
C: Erm....well I can't do that, erm.....when will he be in next?
W: Tomorrow, can you tell me what the call is about so I can tell him later?
C: Sorry I can't do that, I can only talk to him about it.
It's a good job Our Lass isn't the suspicious type!