Ceiling light won't switch off?

Hi all, really hope you can help as this is doing my head.

I'm replacing a three bulb pendant with a single bulb. This light can be controlled from a downstairs and upstairs switch.

The ceiling has three cables coming out. Two of the cables holds a red,black and green/yellow wires (A,B). The third cable holds two red wires and a green/yellow wire (C).

I have tried so many different combos of putting the cables into the the new fixture but cannot get it to work. Results have been flickering light, no light and now a permanent light.

Currently I have cable A in, with the black wire in N on the fitting with the red wire in L and then earthed. I have then taken cable C and put two reds into the LOOP and earthed. Cable B is not connected at all. This has resulted in the light being permanently switched on. I flick the wall switches and there is no response.

Off the top of my head the last config I had was with cable B connected and cable A not being connected and that resulted with no light at all and neither switch responded.

Can anyone help please?????