help 1.8l 92 golf brake problems

My girlfriends got a 1992 VW golf Gl and the brakes keep going out, well the passanger side goes out first then it only has the drivers side that barley works so we bleed them and they work for about 24 hours then they go out, we bleed them several times and the master cylinder seems to be good and all the hoses are good any Ideas please help does it neet a sim card or somthing