I've never tried. How do you do it? Presumably there should have been some paperwork form P. H. Jones (British Gas) which I have never received. The unit was installed on 29th April after them pratting me about, twice failing to turn up on the appointed date.
Actually a correction: I did receive some paperwork - a questionnaire about the work of someone who didn't turn up, and a unit that didn't exist.
Most things sold retail to the public must have the price displayed before they can be bought. Sale of Goods & Services Act covers that I believe. I can't believe that EV posts are any different - they should be displaying the price on the screen of the post, or a sign/sticker.
I have just had a call from Darren at PH Jones (aka British Gas). He wants someone to call tomorrow to find out the serial number of my charge unit. Apparently the guy that fitted it failed to make a note of it. That was more than 6 months ago.