ULEZ Charge

Out of interest when entering a vehicle registration to pay for the London ULEZ fee, if it says details for the vehicle cannot be found and you're 100% certain the registration has been entered correctly, has anyone then proceeded to not pay and did you receive a fine as a result?

My sorned vehicle was driven to garage to have some work done, and driven through the ULEZ, and when I went to pay it says no details of this vehicle can be found, I paid anyway.