I've known 'just take your shopping and go' and 'let me make a note of your details', but never 'put your bags down and bugger off but please do comw again'.

And why would ordered and paid for shopping be so inaccessible? It's not going to be locked away in a vending machine type thing right, you just need to show up with ID/log-in and collect it. Or so you should.

I’ve only known “sorry, the till is down” and line ups as far as the eye can see.

It's ridiculous that everything stops, but I do understand.

The pickup is even more ridiculous. Like you say, it's already through the system. They would just need to mark it as delivered later.