MOT question

[Captain Peanut]

I'm hoping that someone can help me with an MOT question if possible.

I bought a new car last week and, when I went for the test drive before buying, I noticed that the nearside wing mirror glass was missing. The garage said that it had been ordered and would be fitted before I collected the car. When collection time came around the glass had been fitted as promised and I thought nothing more of it.

However, on the way home I tried to adjust the mirror and found that it didn't move when using the interior control. I assumed that the glass wasn't clipped in correctly and just got on with the journey. I checked this over the weekend and found that the glass had been stuck to the wing mirror unit using what looked like some kind of black adhesive. This meant that I now had no wing mirror glass and no way of reattaching it as the adhesive wouldn't budge.

Normally I would have just sourced a second hand unit and left it at that. My problem is that the garage MOT'd the car before collection and, according to the MOT manual, a mirror that cannot be adjusted is reason for failure. Is this correct and, if so, what implications will this have as the garage have issued a new MOT?

Thanks

Olly