Shoutbox

You might have trouble complaining about text delay times to be honest, there's nothing in your contract with Orange that says that text have to arrive promptly.

This allows the networks to conserve resources because they can use Packet switching to send text messages instead of Circuit Switching.

As long as they're getting there eventually, there's not much you can do. (Although in my experience, ringing Orange regularly to nag them can work well for fixing issues)