https://www.gtcs.org.uk/knowledge-base/sections/change-update-your-registration-details-mygtcs
Change/update your registration details (MyGTCS)
update your registrationchangedetailsmygtcs
https://www.gtcs.org.uk/knowledge-base/articles/mygtcs-error-messages-explained
MyGTCS error messages explained
error messagesmygtcsexplained