loose UPVC door handle ?

hello, handle to my UPVC door to back garden has gone loose . it has quite a lot play in it . when i checked it is not a normal handle . ( where two screw to take out handle and spindle) . it has one small screw inside of handle which tighten handle on spindle.I used l key to open it which is causing whole problem and that has gone loose on spindle .
i planning to replace whole handle unit but not sure how i can remove it . tried every bit ( removed lock and other screws) but spindle is not coming out

one more thing spindle is not square one it looks like round extension fitted on square one