How do I wire this confusing light switch?

[nwhoran]

So I had a malfunctioning single gang switch in my garage and opened up the box to find 3 wires:

1 black red earth - seems to be providing power
2 yellow blue red - which is the circuit for the garage switches
3 yellow blue red - which is somehow sending power to the upstairs bathroom

Not come across this before so would value input on the best approach to wiring it

 

[SparkyChick]

Do you have a picture of how it is actually connected at the moment?

 

[nwhoran]

Do you have a picture of how it is actually connected at the moment?

Yeah the photo is a bit confusing so I've updated my dodgy schematic. I've only just moved in, the bathroom lights seem to be working fine but the garage switches aren't controlling anything and the lights are flickering. Something not quite right but struggling to get my head around it!

 

[Timbo]

At a guess, the t&e cable you marked as power is live and switched live from the light fitting, and the live and neutral feed will be at the fitting.
Are you able to post a picture of the wires at the garage light?

 

[nwhoran]

At a guess, the t&e cable you marked as power is live and switched live from the light fitting, and the live and neutral feed will be at the fitting.
Are you able to post a picture of the wires at the garage light?

Hi Timbo, this is what it looks like at the light

 

[Timbo]

I think there must be a junction box (or more than one) somewhere in between that lot.
You probably would be best getting a spark in to sort it out. If you post your location, there may be a forum member near you able to help.