[What is this called!?]

Ahhh that’s amazing thank you so much Pete!! ??

[What is this called!?]

Hello, my boyfriend bought me a Fox as my first car about 18 months ago and I’ve absolutely loved driving it. It even got written off and I bought it back to fix it and drive it again ?   

 

But I was driving up the motorway a few weeks back and something came off my car as I hit a pot hole. Turned out it was the flat black plastic plate thing behind my wing mirror on my drivers side. 

 

Does anyone one know what this is called please and where I can get another one? I feel I’ve searched the whole internet with no luck so far!?