Cannot access Tahoma Switch ?

Bonjour,
I can no longer access Tahoma switch from app in France; it doesn’t recognise email (of previous conciergerie) and password I used to use. When I try to set it up as new installation (in order to access) via the app it says the box is linked to a different account and won’t let me progress any further.
The previously linked email account is one that I no longer have access to so even if I try and reset the password I can’t receive the email to tell me how to reset.
The PIN is 2203-1682-8446
Can you help?
Merci,