@ktbveccs, since this is such an urgency, the first thing I would recommend doing is getting a certificate in place, and then we can worry about automating the process so this doesn’t happen again. The easiest way to do that without in-depth knowledge of the server is to use one of the browser-based clients; I recommend https://zerossl.com/free-ssl/#crt
Here, the easiest way is to use HTTP verification, which will require you to place a specially named text file (with specific contents) in the .well-known/acme-challenge directory on your web server. So, if the file was named abcdef, you would need to have it so that the file can be loaded by navigating to `http://www.bveccs.com.au/.well-known/acme-challenge/abcdef. (If there’s an SSL redirect and you see a certificate warning, that’s ok. Let’s Encrypt will still retrieve the challenge file.)
To do that on ZeroSSL, you will need to enter an email and the list of domains you wish to get the certificate for. I would be sure to use all the domains listed on that original certificate. Note that each domain will get it’s own challenge file. Make sure they’re all accessible at the right URLs! After this, it will generate an account key that you should save. We’ll just hang on to this for now until we get the immediate problem sorted - it’s not critical for anything. After that, you will be provided the challenge files to upload. Make sure you pay attention to the period in front of well-known, a lot of people miss that. You’ll probably need to create these directories wherever you would normally add files to the server and then upload the challenge files.
Once all the files are there, you can tell ZeroSSL you’re ready, and it will instruct Let’s Encrypt to initiate the challenge. If all goes well, you’ll be presented with the certificate, private key, and CA chain. You should have a place on cPanel to paste the contents of these files, which will install the new certificate!
I’m off to bed now, but let us know if you have any issues and hopefully someone else can jump in!