You can change the email address of your TomTom account at https://www.tomtom.com/en_gb/mytomtom/accountdetails/
I changed my email address by clicking the link you provided. Unfortunately the forum's notifications are still sent to my old address, it looks like the two databases are not synchronized. Is there something I can do?
See if support can do it for you:
02079 490 134
Monday - Friday: 9:00 a.m. to 5:30 p.m.