Whilst watching on demand it freezes , says this is temporarily unavailable and takes me back to main menu , which says there is a network error , after a few minutes it clears and I can re access on demand and carry on watching any ideas as getting beyond a joke
On demand is accessed via network connection and if for some reason the network connection is lost then you would experience the fault you described. Wi-Fi connections tend to suffer this more than a wired connection and using the 2.6 GHz instead of the 5.2 GHz wi-fi can cause issues especially if mobile devices are using the same frequency.
You can't learn anything from a mistake until you admit that you've made it.
Sorry to hear about the trouble you've had with On Demand - have you noticed if this is the only service that's impacted? As michaeldavis said above this error could be caused by a problem with the internet connection.
Please check here: virg.in/service for known issues that could account for the problems you've experienced, if you sign in you can also run tests on the equipment.
If there's no problems detected following those steps please let us know so we can take a further look.