Appologies for the site outage, checking the logs shows a lot of Search Engine Bot requests doing really stupid things with the Tax Selector and Currency Selector just before the server locked up, the server itself doesn't have a lot of memory: so I just wanted to share our solution - again using our Content Management Plugin:
we just added a new "block" rule to our firewall for User Agent requests that contain:
SeznamBot,MJ12bot,AhrefsBot
checking the windows logs shows the server was still running, but not accepting requests until we powered down and up again.
the traffic has now reduced, the site is back and we're still monitoring.