Changed URL, can’t login

I’ll try and explain this the best I can… A client came to me to populate their website. Their friend in Brazil had half developed the website but it needed re-branding. The site was on a Brazilian server but the memory was too low and caused media upload problems. My client then transferred the website to Crazy Domains in Australia, from then I logged on through his new domain. However, the URL for the site was still the old one. I completely created the website for my client, then from the WordPress platform I changed the URL in the settings to the new one. Instantly I couldn’t login from either the old url admin or the new url admin. I fully backed up the website using the Updraft Plus plugin, but the files are only accessed from the admin platform. Crazy Domains have not been able to help. Does anyone have any advice? Otherwise I’m going to have to start the website from scratch again. Cheers.

The page I need help with: [log in to see the link]