I had a 'senior moment' in Tescos last week. I usually pay by card but as I had a bit of cash in my purse, I decided to use that. My bill came to £26 and I gave the lad on the till 2 £20 notes. He gave me my club card back along with vouchers for this and vouchers for that. It wasn't until I got home that I realised I was concentrating so hard on the vouchers that I didn't notice he hadn't given me my change, which was £14. I thought I will never prove this but Tescos were great. They checked the tills the next day and gave me my money back with no quibble.
I kept thinking of the old days when they used to say 'please check your change as mistakes cannot be rectified later.'