Hi all I have a problem with selecting gears after I get above 2000rpm in my 1.7CDTi astra H 2004

If I shift below 2000rpm then it's a little notchy but over that and I have to wait a second between gears of force it in

I have tried to adjust the cables under the gear shift but don't know if they are stretched ?
In the Haynes manual it shows you the plastic threaded part showing out of the clamp , mine are completely inside the clamp ?
I also checked the selector on top of the gear box and there seems to be alot of play in the mechanism where the small white plastic part is

Does any one have a clue if these are right or fancy having a look at there's to see