changing ssl so it covers https://www.mysite as well as https://mysite

Hi I’m really sorry, this question is probably incredibly thick but I’ve hit a problem.

I’ve had really simple ssl on my site for over a year (paid version).

However, recently, my site broke after trying to install the new version of wordpress. I did a reinstall, it went horribly wrong but luckily my ISP had a back up and reinstalled that.

However, during/before the breakage I paused really simple ssl.

After fixing everything and switching Really Simple ssl back on, I’ve discovered that my ssl certificate, which used to cover https://hamgee.co.uk and https://www.hamgee.co.uk no longer covers the www version of the site name.

I do a lot of facebook advertising and email marketing have many, many orphan autoresponder pages with links to free books such as this one; https://www.hamgee.co.uk/freens.html which are now no longer secure. Most people put the www in unless they are following a link. Does anyone know how I can edit my ssl certificate so it covers both again?

I have tried and tried but I cannot for the life of me work out where or how to edit the certificate information so it will cover both (the original did). Worse, despite the fact I paid, it now seems to think I haven’t paid and insists I update to pro to access human support. Worse, if I try to uninstall and then just reinstall it and hope I get an option to do it right this time, it asks me questions I don’t understand and cannot answer so I daren’t.

All I really need to do is force it to renew the ssl certificate an add the extra permutation of the name with the www at the right point.

I apologise for being too stupid to live, my metier is writing books rather than code and any help you smart people can offer would be hugely appreciated.

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