Trying to replace basin tap's cartridge

[akist]

I was trying to replace the cartridge on this Hansgrohe tap.

The retaining nut is plastic and it is very stiff and distorts when I try to undo it. If I press harder it will snap.

Is there anything I can do other than replacing the tap?

 

[jj4091]

Is that a screw going through the front of the tap. you will probably need to remove that if it is. If not you need a box spanner or socket that will cover all the flats and prevent distortion as you undo it.

 

[akist]

Thank you and I thought about that, and then worried it would strip the head right off. But I iwll try, nothing to lose.