Overcharged 3 times in less than 2 months

In the past month I had to return to Clicks after hving purchased something. On each occasion I was over charged. Today the item on the shelf was marked R35.90 and I was charged R59.90! This is unacceptable. It is an inconvenience to have to return to the store because often one only discovers back home that the item was incorrectly rung up. The fact that this has happened no less than 3 times in less than a month, reflects badly on Clicks. Hopefully other customers also check every time they shop at Clicks.