This is not a problem with anything you have done or your code. It is a problem with the hosting provided to you. The socket is used by mod_cgid and without it your scripts won't run, hence the 503s. I suspect that your hosting providers are inadvertently deleting the socket file from /var/run periodically and a subsequent (again, presumably scheduled) restart of apache eventually reinstates it.

The response you posted from your provider is worrying in that they seem not to know that this socket is integral to apache, that the error message is an apache one and that neither of these things are anything to do specifically with your scripts. Perhaps it's time to move to a more clued-up hosting provider?

When this happens our business is dead in the water.

In that case it's definitely time to move to a more clued-up hosting provider. Good luck.