For years, many Kenyan shoppers have walked away from supermarket tills with the same uneasy feeling.

"The price on the shelf is not what I have been charged."

Most paid anyway. Some noticed too late.

Others assumed they had simply read the price tag incorrectly.

Now, those complaints have caught the attention of the Competition Authority of Kenya (CAK).

The regulator has opened investigations into Naivas, Carrefour and Quickmart following complaints that some products were advertised at one price but customers were charged a higher amount at the checkout.

The investigation could expose what consumer rights advocates say has become one of the most frustrating shopping experiences in Kenya.

The difference between the shelf and the till.

According to complaints under investigation, one customer says he paid KSh1,120 for a drink at Naivas despite it being promoted online at KSh899.

Another customer claims he was charged more than the advertised price for cooking gas purchased at Quickmart.

Carrefour is reported to have refunded one affected customer after the complaint was raised. The matter nevertheless attracted a warning from the regulator.

The Competition Authority is now expected to determine whether consumer protection laws were breached in the remaining cases.

The investigation comes as supermarkets compete aggressively for customers through weekly promotions, loyalty programmes and heavily advertised discounts.

But consumer groups argue that promotions mean little if customers ultimately pay different prices at the checkout.

Many shoppers say the problem is not limited to three supermarket chains.

It has become common for customers to arrive at the till only to discover that a discounted shelf price has not been updated in the billing system.

Some customers notice.

Many do not.

That raises a bigger question.

How many shoppers have unknowingly paid more than the advertised price over the years simply because they trusted the amount displayed on the shelf?

Consumer rights experts argue that the burden should never fall on customers to identify pricing discrepancies.

Retailers are expected to maintain accurate pricing systems and honour advertised prices unless the mistake is clearly communicated before payment.

Kenya's Consumer Protection Act prohibits misleading representations that influence purchasing decisions.

If a customer chooses a product because of the displayed price, only to be charged more at the till, regulators may examine whether the practice amounts to misleading pricing.

The investigation is likely to put supermarket pricing systems under fresh scrutiny.

It could also encourage more customers to check receipts before leaving stores and report any differences between advertised and charged prices.

For many shoppers, the issue is not simply about a few hundred shillings.

It is about trust.

Customers expect that the price displayed on the shelf is the price they will pay.

Anything less undermines confidence in retailers and raises questions about whether enough safeguards exist to protect consumers from inaccurate pricing.

The Competition Authority of Kenya has confirmed investigations into complaints involving Naivas, Carrefour and Quickmart. The investigations are ongoing, and no findings of wrongdoing have been made against any of the retailers at this stage.