nick,
if you want help, i would suggest sticking to the topic. you can save your rants for somewhere else.
there is nothing that i see in your blurry screenshots that help indicate the problem.
i went through the trouble of creating an account on your website, but it seems that you do not ship anything to your own address or some other random address in the UK.
i would need to see the storefront where this problem is happening as i am not able to reproduce it on your own site due to your configuration. i did see problems in your OPC setup. see:
https://www.dropbox.com/s/4jbyt4pan5...19-01.png?dl=0
and
https://www.dropbox.com/s/cw7j5cfb45...20AM.webm?dl=0
i need to be able to get to a page that looks like this from your screenshot to help resolve this problem for you and your clients.
https://www.zen-cart.com/attachment....6&d=1650452517
best.