We were over charged at Tesco

Since we retired from front line retail back in September we have been shopping at many different stores both independent and multiples. The store we have used most is a Tesco Metro which is just 100 metres from our home. We have had good service from the store on nearly all visits, but yesterday something went wrong. We were over charged for all our loose purchases, some feat. What happened was that checkout assistant was resting the handle of the handheld barcode scanner on the built in scales. This cause 2 normal sized apples to weight at 750grams. We bought 3 different loose products and when we weighed them on our own scales all of them were between 100g and 300 g less than was stated on the Tesco receipt. We went back to the store and spoke to the assistant at the customer service counter. She needed to get the checkout supervisor involved as the products required reweighing on a checkout. This done the supervisor returned with another till slip and the pair of them attempted to rearing our purchases on to the till at customer services. This was hugely time consuming as they needed to manually enter each products PLU and the weight. Eventually we were offered a refund of 13p which we queried and the Tesco's employees took another look at our original receipt and we pointed out that they had missed an item that was at the end of the ticket. This found they made a refund of 99p and we went away a little less than happy. I just wonder how many other customers had gone through that checkout that afternoon and how many we're over charged. Even more worrying, just how many supermarket checkout staff operate in this way and are checkout supervisors trained to lookout for this sort of bad practice. Hum, I can't say that I have ever noticed it before, but I will be on the lookout in future!