I literally was unable to purchase something from Currys on my phone, it was so bogged down in JS madness that it just didn't work. It would only work on my computer, and then only in Chromium (the payment flow just stopped loading after entering the card details on Firefox). When I did manage to place the order, the payment was processed twice, so that white loading screen in Firefox did so something. When I picked it up, I was told that they can't process online returns, I would have to take the extra one away, arrange a return online and then bring it back.
You are, of course, exaggerating a bit for rhetorical effect, but it is indeed too close to home. The bulk of my time was spent grappling with things that frequently give me a hassle on real websites.
The dialog box
The strenuous password requirements
Especially the "select all pictures of" bit. Anyone who has tried browsing with a proxy can confirm.