The normal configuration would be:
* 3 blacks two which are neutrals and one which is a switch live (live coming from the switch, this should be identified by a red tag/sleeve but often not!)
*3 reds this are all live, one come from a previous fitting on the circuit, one goes to the next on circuit, the other feeds the live to the switch (where switch live, black sleeved red, returns this to the light as mentioned above)
* and three CPC/earth (this must be existing and tested to prove there is a path to earth if you are installing metallic fittings)
So:
* The two neutrals(blacks) go to the neutral blue side of lamp
* The switch live (black sleeved red) goes to the live brown side of lamp, this may need confirming, so a multimeter or an approved voltage indicator would be a handy instruments to have
* The three reds are all connected together in the live loop (this is not the live brown side of lamp) Some fitting supply a loop in live terminal, some don't. If the loop in live does not exist, then a terminal connection block is used.
*The CPC/earths go to the earth terminal of the fitting.
Hopefully that will resolve you issue and give you a little understanding on how some lights are wired up.
These diagrams maybe helpful
And looking here also
//www.diynot.com/wiki/electrics:lighting:two_way_lighting