No it wasn’t my fault but the stupid DNS provider’s.
They had a partial outage of their service for the whole weekend (even their own website wasn’t reachable) and didn’t answer ANY of our calls or email enquiries.

As a result all of the ~20 domains that I run on this server will be migrated to our own DNS servers.
HowtoForge has a good tutorial on MyDNS which we will try and most probably use.

Sorry again for the outage and I hope with taking the matter in our own hands, such things won’t happen again in the future.