Replacing Light Fixture in Bathroom, but has 4 sets of wires in a mess

Question

I took out a light fixture in a bathroom with the intent of installing a new one before and I came across 4 sets of wires. This bathroom light (I think) is connected to an extractor fan and is on the middle floor of a three floor house and connected to a three-switch box that controls the bathroom, middle corridor and downstairs corridor lights. The original setup of the light fixture is in the photos that I have attached below. Within these the wires are:

• Green/Yellow, Brown, Blue
• Green/Yellow, Brown, Blue (with black electric tape tag)
• Green/Yellow, Brown, Blue (with brown electric tape tag)
• Green/Yellow, Black (with brown electric tape tag), Grey

How they were connected to the original bulb is pictured below.

I have attempted to connect these cables up in the following way: (with purple denoting the brown tag)

However, lights downstairs and lights on the middle floor keeps tripping the entire house sockets and lights breaker. How can I go about effectively fixing this? Thank you

Edit: Based in UK

Answer 1

This is quite a the sticky wicket. So to be clear, there are four cables entering the light fixture, all with three wires contained in the cables. All four cables have green/yellow wires, three cables have brown and blue wires, and the last cable has a black and a grey wire.
Most likely, the black and grey cable is your line voltage. I would take all of the connectors apart and take a reading on the black and grey to confirm. If you get no reading, try flicking on and off the light switch. If you have also switches at the bottom and top corridors to turn on and off the corridor lights, then it's quite likely that two of the other cables are the "traveler" cables for the two three way switches. The final cable would most likely go to the fan, and be connected to the red and blue wires which I understand to be your light fixture.