No need to just email, you can send a fax and also a letter to them. Also, get in touch with the UK consumer council and say that you are unable to contact triumph. I am sure that would help.e
Here's the fax number 001 44 1455 453005
Here's something interesting from the T site:
"To discuss Triumph franchise opportunities please contact: Mark Burrows, Dealer Development Manager, Triumph Motorcycles Limited, Normandy Way, Hinckley, Leicestershire LE10 3BZ
email:
mark.burrows@triumph.co.uk
Please note that we are unable to respond to any emails submitted that do not specifically relate to UK dealer franchise opportunities."
Seems they are only interested in making money and not dealing with issues.
You could always email

ressadmin@triumph.co.uk but I guess they might tell you to p-off which is another way of saying Go Your Own Way