Providing you have the account password (and I think it's possible to be added as a named contact for the account as well) they should be happy to discuss it with you. They'll certainly discuss anything with me.
I had a similar issue to this one where I was advised I needed an upgraded cable fitted between my property and the green box. They said they needed access to the property, so I booked the day off work. One hour after they should have arrived I phoned CS to find out what was going on and they were adamant that the work had been completed. I step outside to look at the cable (on the off-chance that they've done it without telling me they've arrived); it's clearly the same cable. It even has spider's webs attached to the covering on the outside of the house so there was no way they'd touched it. Even with this evidence I had a hell of a job convincing CS that the work had not been completed.
Ed.