No installation manual with new cooker?

I've recently purchased a reconditioned oil burning Rayburn Range from an Irish company. We paid €3,300 for it along with the trade in of our old range. The price was for delivery only as I knew my dad, a heating engineer could fit it for us.
However we soon realised that it doesn't come with a guide for installion or an instruction manual for the burner unit. When we asked for one we were told one didn't exist as they had it patented themselves.
I presume we will be able to install it with their help over the phone but we are worried that we may have difficulties down the line servicing it. The company said that people use their men to repair and service them as needed. This was not explained when we agreed to purchase one.
So, my question is, can we be sold an appliance without an adequate installation guide?

You could try digging through their website: http://www.rayburn-web.co.uk/index.asp

Well, it was re-conditioned, not new. So it may be missing some things, like the manual. It's probably a case of buyer beware although I don't really know...

What is the make and model of the burner?

Thanks for the replies.
Although the range may be reconditioned the oil burner is new so we still expected an installation guide for this. I'm not sure of the make and model of the burner as the company say they have it patented and made in Germany. I am still hoping to find out from the company that sold it what the make & model of the burner is.
As the oil burner is not in itself from rayburn, the rayburn website doesn't have the info I need.
Do I have a ten day cooling off period for something like this?

Would it be possible to get a copy of the patent from the Patent Office!