You definately should be getting a better service than you have experience so far.
so, your vehicle has been inspected and declared a total loss (written off). Firstly get all you documents together as they will need these.
V5, mot (if applicable), service history, purchase receipt, copy driving licence etc
Now the more difficult part, your claim is being looked into further as there is an issue of the facts surrounding the insurance of your vehicle. When the policy was taken out NUD were told that they were insuring a standard vehicle and therefore charge you the premium for this. Now they have found out that it has been modified they will need to talk to you via a claims investigator to obtain the facts. Give them all the information and based on this they will make a decesion.
They then have 4 options:
1. the misrepresentation was deliberate to obtain a cheaper premium. This could lead to them cancelling your insurance and declining the claim.
2. the misrepresentaion was not deliberate but had they know the facts they would not of insured the car. Again the claim will be declined.
3. As 2 but the would of insured the vehicle at a higher premium. In this case they will deduct the increase in premium from the value of the vehicle.
4. no further action is required.
One more point is that NUD in Liverpool is closing so moral/customer service may be lower than normal (no excuse but just so you know0