citroen dipatch 2005 1.9 diesel 815 enterprise?

what happens is that you be driving int hird gear and then all of a sudden the gear lever slips out and the same in 5th gear.also the gear lever in the van is so loose in all the gears the lever can move side to side freely where as in other vehicles you dont have much movement when the gear is engaged.ive changed the selector cable and still have the same problem was thinking it was the bushes on the cable. if anyone can help plz ring me on 07790951076.thanks