If you look carefully, you will find that you have two cables in one switch and two cables in the other?
If so, proceed as follows:
Turn off the power to the fusebox
On the switch with two cables you should have one cable with two wires (black and red) and another cable with 3 wires (red yellow and blue).
With the 3-wire cable connect:
red to terminal marked C on the switch
yellow to terminal marked L1
blue to terminal marked L2
With the 2-wire cable connect:
red to L1
black to L2
On the switch with one cable (it should be a 3 wire cable) connect:
red to terminal marked C on the switch
yellow to terminal marked L1
blue to terminal marked L2
Then turn on th epower and all should be OK.
There are drawings on how to do it at
http://www.diynot.com/forums/viewtopic.php?t=7553&postdays=0&postorder=asc&start=30
If your installation has different cable colours, or layout, or different switch markings either come back here and ask before you do anything or call in a competent sparky.
Good ones are available at
www.competentperson.co.uk
Hope he comes back. Was it all over the lights?
TTC