Loblaws complaint: Overcharge

Purchased grapes at $2.99lb the charge was at $11.00Kg. 2.99lb is $6.60kg. by any standard. I showed the young clerk the problem, she called another one who tried to convince me, I was confused for the price is per lb but the price per kg is what 2.99 is, 11.00. I am senior who grew up on KGs and knows the relation to Lb etc. Your clerk had no idea what it was. Kept claiming she was right because she was told this is how things are. So I am confused, not her. Then comes the manager, same thing has no idea Lb vs Kg, Finally I managed to explain to them, then they blamed computer, Yes, it was it’s fault, but they were supposed to change the price from4.99 to 2.99lb. How many customers went through paying double the price? Would any of them pay 100K for 50 K car?
I lost appetite for that grape and asked for refund. No apology at all, It was my fault that I caught the mistake. Sadly this is at least 3d time this happened at this store, and all with grapes. Never an apology always an attitude it was my fault I caught the mistake.
I believe I wrote you a note with same problem some time ago, maybe in diff form. Not heard from anyone.