Centre change

hey guys. just wanted to follow up on my last post as this is a Bit of a matter of urgency. how do i change test centre after booking my test on the site? Can’t seem to find it and i feel like i’ve searched all over the site lol unless i’m blind but i genuinely don’t know where I can change it. Test is coming up in the next week but my circumstances have changed since i booked the test. help is really appreciated! thanks a mil