Don't user.... They use a email address other then their domain name;
sales.3mobilefones@4ultd.com

and the contact address is different to the domain holders address:

Website:
Mobile Media Systems Ltd.
Cool New Mobile PO Box 8895
Bingham
Nottingham
NG13 8XA

Domain holders address:
Registrant:
Mobile Media Systems
Po Box 7404
Radcliffe On Trent
Notts, NG12 3ZY
UK
Domain name: 3MOBILEFONES.COM
Administrative Contact:
Jukes, Chris domains@iacl.net
5 Acorn Business Park
Commercial Gate
Mansfield
Notts, NG18 1EX
GB
+44 8700 12 1234
Technical Contact:
Jukes, Chris domains@iacl.net
5 Acorn Business Park
Commercial Gate
Mansfield
Notts, NG18 1EX
GB
+44 8700 12 1234
Registration Service Provider:
Internet Advertising Corporation Ltd, domains@iacl.net
+44 8700 12 1234
+44 8700 12 1089 (fax)
http://www.iacl.net
This company may be contacted for domain login /passwords, DNS /
Nameserver changes, and general domain support questions.
Registrar of Record: TUCOWS, INC.
Record last updated on 05-Oct-2006.
Record expires on 01-Dec-2006.
Record created on 01-Dec-2004.
Domain servers in listed order:
DNS1.IACMAIL.COM 195.182.184.1
DNS2.IACMAIL.COM 195.182.184.2

From the "About Us"
"We joined forces with 4U ltd back in 2003"

NO,  no one here has had any experience !

(HINT, put  SUBJECT in the SUBJECT line !)