I have just been humiliated by Waitrose after self-scanning a big shop in my local branch, when I was “randomly” picked for a re-scan. I admit I didn’t read the terms and conditions.

I saw a display in store a few months ago about self-scanning and so I registered and started shopping. It has been really good, making shopping faster as I don’t have to re-pack. But I had never heard of having to be “re-scanned”. The staff member was a bit matter-of-fact and I was embarrassed. The supervisor told me it was in the terms and conditions and store policy. I was beginning to get angry. I said I was in a hurry and hadn’t been warned of this (of course, I now see this is the exact point). I felt like a thief as I had caused a scene but hadn’t done anything wrong.

The manager just said the same thing – store policy, terms and conditions and so on. I asked where my shopping trolley was now, and it was already almost entirely through being re-scanned at a conventional till with a girl packing my bags. I was very cross and said my bags were packed as I wanted them, so what had been the point of me doing all that scanning and packing?

They said they were packing them the same way. I asked whether the till scanning showed the same as my self-scanning device, but she said she didn’t know, that it had turned off.

My main bugbear – now I understand the thinking behind the re-scanning – is that however in their rights they were, I couldn’t help my knee-jerk emotion of feeling humiliated and guilty, though I’d done nothing wrong. We spend a fortune in Waitrose every year but I am having a rethink.

CS, Eastbourne, East Sussex

Inevitably, human error and unfamiliarity using the hand-held Quick Check scanner – can trigger mistakes.

It also places huge trust in shoppers to scan all the items and must be a temptation for prospective shoplifters – which makes this a highly sensitive issue. Anecdotal evidence suggests that retailers are losing millions from “self-scanning thieves”, which is why supervised checks are carried out. Our understanding is that if a random scan (triggered in roughly one shop in every 200) reveals a noticeable discrepancy between the total triggered by the shopper’s self-scan and the subsequent one carried out by staff, a “red flag” is raised on your registered card. This means you will be subjected to further re-scans to find out if an error was a one-off, or deliberate behaviour. You would have been better prepared and less shocked if you had read the terms and conditions.

Waitrose says: “When signing up for Quick Check customers agree to random re-scans, although we do our best to ensure these aren’t too inconvenient. We are very sorry CS feels disappointed with the system and that the result of the scan was not given after it was requested, as it should have been. We can confirm CS’s scan was correct, so no additional re-scans will be generated (beyond normal random re-scans).”

Waitrose has been in touch to explain this and apologise with a goodwill gesture. To any readers traumatised by the prospect of a re-scan, we would recommend that they do only small shops, or stick to conventional tills.

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