HABITATION DOOR - WORCESTER MODEL

Can anyone help please. I live in NZ and have a 2011 Auto sleeper. Worcester. The door has never shut properly from day one, despite repairs to the lock and hinges.  Told to "slam " it shut.'
Now looking at replacing the entire door, as the plastic insert has discolored and cracking up. Trying to source one in the North Island of NZ. Not sure if posting this on the UK site will bring any joy, but worth the try. Maybe someone from NZ might see my post.
THanks.
Jean

I was advised never to slam a door. I use a 2 stage closure - gentle push followed to engage the catch followed by a firm push on the handle to close - works every time.
Rich..

My (same door) has had the plastic reveal of the window (internal) that Dometic refer to as the "blind panel" crack and split and shrink slightly I am 100% certain that this is due to sun damage rather than the door closing.

OK the panel is now 10 years old  but it has had visible deterioration for at least 3 years - the motorhome has never been out of the UK - I dread to think how those in souther climes long term have faired!

My door also needs a firm slam by a hand placed about 2/3 up the door to ensure a proper closure of both catches - both catches failed and I was horrified at the springs which actually secure the door - it was far more secure with my jerry rigged pair of shoe laces securing it!