Mercedes Benz CLK battery went flat now wipers only work when lights are on full beam

i left the car in my garage for about 3 / 4 weeks without starting it and when i went to start it the battery was totally flat i recharged the battery and the car started up straight away then i checked everything was working ok but then noticed the window wiper arm has to be in the high beam position for them to work so now i cant drive in the dark just incase in need to use the wipers and high beam comes on .

does anyone have any ideals before i have to take it to a mercedes garage . thanks craig