brogon

Hi all has any body have any idears of what is causing breaking problems at low revs.when i have applied the foot break slowing down to trafic lights after first depression of the foot break is verey hard to depress but after reving up by a few seconds the break is ok. please help if you can. many thanks for any feedbck my car is a Galaxy TDI 115 2002. Thanks Brogon