On inspection, I have found that the old fitting has 3 connectors on it. 2 are for live (red) wires and one is for nuteral (black) wires. There are 2 sets of wires in the ceiling that attach to this fitting. The live wires go to the live terminals and both nuteral wires are joined and go to the nuteral one.
The new light fitting only has 2 connectors on it, 1 for live and 1 for nuteral.
I have tried joining both live together and connecting to the live connector and doing the same with the nuteral wires to the nuteral connector, but this didn't work.
I am loathed to give advice as to bathroom wiring as mistakes can be lethal. But re-reading what you have said I expect it is a standard ceiling lamp. Both in the projects section and on other questions raised this has been dealt with. The main thing is lights are wired as a string with the power going from one light to the other so they all have three connections plus earth. Look at "Help lighting, 3 red 3 black 3 nutral" where your question has already been answered.
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