overheating

can anyone help had head gasket done on my 320i 1994 about a month ago they replaced rad, thermostat, waterpump ever since i have had nothing but problems, seem to be able to do about 100 miles then plays up when i pop the bonnet to have a look the right hand side of rad and top hose is warm but left hand side and bottom hose is cold to make it driveable i have to bleed by the roadside, def doesnt seem like its losing water can anyone help