How can I re-connect my 2 way light switches?

it's not as easy as that, I have two double gang 2-way circuit upstairs and a Builder disconnected all the wires to sink the back boxes to have them all flush when plastering but did NOT re-connect them properly so the wrong lights come on when you flick the swich.
What I should have is
1) 2-Gang switch downstairs serving a) a seperate one way light which does work OK. AND b) 2 way light upstairs. in this switch there are 2 black wires connected to a block but not the switch?
2) 2-Gang switch serving a) 2 way light with the previous mentioned switch and a second 2-way light along the hall.
3) 1 Gang switch serving the second 2-way gang of the switch last mentioned.

Now all of the 2-way circuits have 3 core and earth wired fitted so I can follow the connections to make sure they are consistent but the there is a 2 core and earth wire coming to each of the switches and I'm now confused. If you turn on switch 3) both lights come on and also if you turn on Gang 2 of switch 2) the same happens but nothing if you switch gang 1 of switch 2.

I think it is the 2 core & earth wires coming to the switches that is throwing me. Any Thoughts would be much appreciated