I was given a quote by a well-known car insurance company for a new car (with another older car) about 3 months ago. I agreed a premium the phone and used the internet to complete. Today, I received a letter from them stating they had taken, get this, a further £600 from my account, because that what it should have been. Looking into what similar insurance firms charged it was roughly the same, but I wondered if they could do this without informing you first. Luckily, I just had enough in that account to cover the cost.
I'd certainly ask them to explain why and say that you agreed the policy on the basis of the quote. Is there a simpler explanation though- maybe some more information came into play such a s exact details of NCD or the car spec was not quite as first thought