How to best mitre pvc coving, pls help

[kilo_4que]

Hi guys, I recently fit some decorative cladding in the restroom and with it I bought some pvc coving. Basically it is the type where you fix the backing i.e. a L shaped length to the corner of the ceiling, cut the front to size and clip into place. So basically it comes in two pieces.

Now the front part i.e. the part we see is just a simple moulding which is very thin. How am I supposed to mitre this as when I place it in my hand mitre saw it doesnt cut properly as it keeps flexing and the cut line always moves.

Please help.

Anyone that has fit these before please do let us know about your experiences with them

thanks

 

[kilo_4que]

Please guys can someone help me here as im really stuck. Ive already cocked up the coving so far attempting to mitre but its all gone you know muffins up.

Ive attempted to cope one side also but no luck due to the fact that the coving is to go in at angles and coping is difficult besides its very slim hence wont cope well.