ABS+ETC lights on (the brake lights are not working) NEED HELP

First thing to do is remove rear light covers and check brake light bulbs, could be as simple as blown bulbs as have seen this problem before and it brings up warning lights on dash .. read link ..

http://www.audi-forums.com/b6-forum/44046-esp-warning-light.html

or other option is brake light switch could be faulty and needs replacing

My bulbs are ok...

brake light switch defective.The switch has three puprposes 1 brake lights 2 engine control unit needs to see the switch on or off and number three the abs/esp needs to see whats going on also from the switch position so replace the switch or check the operation of the switch with a multimeter or vag com.

Do you know what the cost may be?

switch £20 ish and to have it checked £50 ish

I just replaced this and all is good. I am no mechanical expert. Just be sure the follow the instructions. When removing the plastic piece under driver. There are 5 bolts. 2 underneath, 1 in the fuse "box" and 2 near the dashboard. The 2 on the dashboard are accessible by "popping" off the piece above the steering wheel. Make sure the Brake light switch locks into place. It was not that bad, only a few hours. The 2 screws on the dashboard had me for a while.

BTW the part cost me 9.50 euros at the dealer.