Daz
Where did you purchase it? Alibaba? Then go to your order on alibaba and file a complaint and ask for support.
Phonenumber? Do you call Amazon if something is wrong? It doesn't work like that with online shops.
I had 5 previous units from different brands. Not one came with an installation instruction, only an A4 with what bunch of wires is for which functionality and numbered inputs where to put them into the unit. That was all.
Did you get that A4 (or Letter format)?
There is quite some info online. And what do you think you're missing apart from the missing install instructions? Because you do not mention that. Please explain.
And note: I do not respond because you were asking for an adult. I understand that you are frustrated, but this is not a friendly way of asking for support.
Edit: You could also do what a lot of buyers do: have it installed by a qualified engineer. It is not rocket science, but it's not peanuts either.