Hi there - the problem is that one of your name servers is still set to use 123-reg, as you can see here:
Name Servers
ns.123-reg.co.uk 212.67.202.2
ns1.wordpress.com 72.233.69.14
ns2.wordpress.com 69.174.248.148
ns3.wordpress.com 207.198.112.47
Please log into your 123-reg control panel and remove the ns.123-reg.co.uk name server, leaving only the wordpress.com ones, and things should return to normal.
Just let me know if you have further questions.