To prevent unwanted parking tickets, speeding fines or road tax queries, you need to let the DVLA know that you no longer own your car. Your registration document (V5) has a section titled 'Notification of Sale/Transfer to the Motor Trade/Insurer/Dismantler'. In new V5s, this is section nine.
You need to complete this with Synetiq's address:
Bentley Moor Lane
Enter 'N/A' in the space for the VAT number and 'Not present' where it asks for the signature of the motor trader. Then sign and date it, the DVLA are happy to accept this.
Detach the slip from the rest of the V5 and send only the slip to the DVLA: