There have been a few documented cases but for a business with many millions of customers I don't think it's a real issue?

My return rate is around average (I guess) and I've never had a problem.

The last incident is where I put the wrong sim card in a phone and couldn't get it out. Just return it I was told and the refund came through as soon as I had printed the label.

This is 100% the direct opposite of what would happen with any other UK retailer.