Voucher ninja. Even an expert supermarket money off voucher user can be caught out

So, nearly got caught out by a voucher this morning.   These particular vouchers arrived at my house in the week accompanied by 3 free dishwasher tablets.  The idea was to introduce me to a brand I did not use  and then use the voucher for £1.50 to buy some more (and switch brands forever, no doubt).
iStock_000006956703MediumI arrived at the supermarket for my weekly shop and I looked at the dishwasher tablets aisle. I picked up a box of the brand I had the voucher for. They seemed good value at 33 for around £5. Deduct the £1.50 voucher from the price and that worked out at just a little over 10p per dish washer load.
I popped them in my trolley and did the rest of my shop.
Then, as I waited at the till, I looked at the voucher more closely and checked it carefully against the dishwasher tablets in my trolley. Both voucher and tablets were for the same brand but the voucher could only be used against a new formula of that brand.
The new formula wasn’t £5 for 33 tablets but £8 (and for a box containing fewer tablets). I couldn’t use the voucher on my £5 box. Even with £1.50 off the £8 box was more expensive per tablet than my usual brand. I took the £5 box back and got my usual, better value brand.
I can’t help wonder if the assumption was I’d buy the more expensive brand when I got it to the checkout rather than go to the effort or changing it? Gosh that would be cynical wouldn’t it?
Well, even if the £5 box had gone through the check out, as a money fighter I would have handed them back at the point the sales assistant refused the voucher (for the £8 a box version). And even if the voucher had been accepted,  I check my till receipts before leaving the store. I would have spotted I’d paid more than anticipated for the dishwasher tabs. In both case, as a money fighter, I would have got them out of my packed bags and handed them back for a refund.
The shop came to £69 and guess what if I spend £80 next time I can have double loyalty points.
You need to concentrate and check everything if you’re not going to get caught out. Glove up when you go shopping.