05 LS Focus aftermarket stereo issue

[Sairz80]

Hi,
so I recently got the great idea to change the head unit for my daughters' car, ordered an Aerpro kit (FP9245MK) for a single din unit.
Has anyone else used this?
We must have got a dud, the posts to secure do not fit, and the company is a little slow to respond (over a week to get a response). They've suggested a few (not so good) quick fixes, none that I would like to do. Possibly another fix (after I wait until Monday for another response) is to return and reorder and hope the next one installs the way it should.

Can anyone else suggest what they've done to get a single din stereo fitted?

thanks
Sarah