julianfoulger

The vehicle registration number is the number plate on the outside of the car (ie the 2 plates you have - front and back) ie https://www.wikiwand.com/en/Vehicle_registration_plates_of_Mexico . I am not sure it will work if the car is registered in Mexico as it could be just for UK reg cars. Have you tried just using the VIN number with and without your Mexican number plate?

You should emaîl them at https://www.radiocodes.co.uk/contact-and-about-us if unsure. The vin number should be enough. You should also buy a 2 fobs (ie 'controls'), the second fob being a spare in case you lose the first. There are 2 different FOBS, depending on the age of your car.. The fobs will need to be programmed to the car..