It looks like they've been putting in place a new offering, instantsite so maybe that has something to do with it. Your 123 parking pages look a little odd also, is that new or just very old?
Were all three owned by the same person previously? if not then it probably is a 123reg problem.
Go through this
Go to DNS and 'reset DNS to defaults'
Check CNAME and TXT are the same as other stored domains
Go to web forwarding - click no web forwarding and save
Check IPS Tag and ensure it's 123-reg
And nameservers, remember 123 reg is useless at showing current nameservers, try putting in current nameservers for 123 reg and see if that works, then give it a few hours and change it to the ones you need now.
If that doesn't all work, pay 50p and speak to tech.
If it's any consolation their turn around time is woeful, I'd agree with that, especially when you can speak to four different people over the space of 48 hours and they and you are none the wiser, their ticketing system must be awful.