If you're waiting for DNS propagation then I'm afraid there's nothing you can do but wait for the TTLs of any troublesome cached records to expire and everyone to start looking at the correct authoritative DNS servers..
Incidentally 123reg are no longer owned by GX Networks (they were sold off a few years ago) - as I say, I've never had any problems with them personally.
But whoever is setting this up for you should probably have explained how things work - if you're doing it yourself, you might be wise to find someone who knows their onions to do it for you (and who can explain these things up front!) - JMHO, no offence intended

[edit] Incidentally - DNS is as DNS is .. it's unlikely to change how it works, fundamentally, any time soon.. heck, DNSsec has been with us since 2004 and is only just starting to get some traction - and that fixes some very real security holes in DNS! Don't fight it, you have to learn to go with it (and to be sure to do it right the first time when it comes to DNS, there's nothing more frustrating than waiting 24 hours, finding you goofed and having to wait again .. trust me, I have that t-shirt somewhere!

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