Yes, contact them yourself, I did. as long as you have all the documentation and have the full datatag info you can change it yourself.
This is the response i received when i emailed them:
Hi and thanks for contacting Datatag,
The details you have supplied have allowed us to locate your machine on the system.
Do you have any of the paperwork from the previous owner? If so, there should be a Section C - Change of Membership Details form. If you do not have this paperwork, please let us know and the relevant form will be either emailed or posted to you, whichever you prefer. This needs to be completed and either emailed to us or posted to us at the following address, regardless of what address is stated on the form itself. The address to send it to is
DATATAG ID – REGISTRATION TEAM
UNIT 2, HIGHPOINT BUSINESS VILLAGE
The standard fee to re-register a machine is £15.50 and if payment is by cheque, it should be made payable to “DATATAG ID LTD”
If you have your V5 certificate please send a copy of the inside pages as well.
Please note that before processing the forms, we check that all the information written on the form matches that on our database to make sure that we hold the correct data. If the information is different, we may have to contact you and ask for extra documentation to be sent (ie. V5 copies, pictures...)