Post boxes in garage forecourts and TG Jones/WH Smith

I haven't uploaded yet, but in my local TG Jones we have a rather bland looking box which doesn't fit any category I can find listed on here. I have also seen one at a filling station in Gomshall, Surrey on the A25. This web site https://www.cvphm.org.uk/ElizabethII3.html suggests they are called Garage Boxes as that was their original location, but some have moved on to the shops mentioned. Is it a category we need to add on to the web site for uploading? Ray