Both brake lights not working

First, I double check those bulbs to make sure that they are in fact good. Buy a couple of new bulbs and try them. Sometimes bad bulbs will look perfectly fine. If that does not work use a test light to make sure that there is power to the brake light sockets with someone pushing on the brake pedal. Obviously the brake switch works because the third brake light lights up so it looks like the turn signal switch is no good but to be sure here is a guide and the brake light wiring diagrams so we can confirm the failure.

https://www.2carpros.com/articles/how-to-check-wiring

Check out the diagrams (Below). Please let us know what you find. We are interested to see what it is.

Thanks for this guide, I found out the multi function switch was bad I had to get a new one cost me $121.00 all fixed!

I have changed my brake light switch on my Astra 02 plate, but the brake lights still wont work? I have checked the fuses, changed the bulbs for new ones and tested the circuit (digi-meter) for power to all connections, and this has come up fine.

I recently noticed that my third brake light at the top center of the rear screen is not working, although the left and right brake lights work perfectly. I drive a 4-door hatchback. What could the problem be? Firstly is the center brake light powered by globe(s) that can be replaced or LEDs? The manual provides instruction for replacing all globes except the center brake light, so I suspect that it may be LEDs that are supposed to last the life of the car. Secondly, could there be two separate brake switches, one for the normal left and right brake lights and another for the center brake light? Where can I locate this to confirm? Thanks and appreciate your replies.

Bulbs and fuse ok, so I'm assuming it's the brake light switch, if so how do you replace?