I wanted to either rent the tool or have them knock out the cups (10 second job), either way I was happy to pay for it. But probably I didn't communicate this very well to the shops by starting the conversation with the word "borrow", though I did add I could give a few quid. So that may explain their initial shirtiness. However, the main thing they were upset about is I had a spare replacement headset part in my hand that I had sourced elsewhere, an online retailer as I admitted. Maybe if I had gone in there with just a bare frame and asked if they could knock out the cups (10 second job) they would have done it there and then for a few quid without any issue.