While retailers do what they can to squeeze extra pennies from consumer pockets, they don’t always pull it off.

The people who work there are only human after all, and that means mistakes can be made. Whether it’s a wrongly labelled garment coming in at a cheaper price, or an online order that’s been packed with too many goods, frugal shoppers will usually celebrate these errors and count the money that they’ve saved.

We can’t say we blame them: it’s not always easy to make ends meet, and sometimes a cheeky saving due to a retailer error can really make a big difference. However, it’s important to understand what the different laws and regulations say, so that you can ensure you’re always acting within the rules.

It’s also worth remembering that some mistakes can get people in trouble. If you notice that your checkout clerk accidently gives you too much change, for instance, it’s important to make sure you hand back the extra coins.

It’s quite possible that an unbalanced till could cause them difficulties at work, and it would certainly be unethical to let that happen knowingly. Here’s what the rules say about some other common situations…

Items advertised for the wrong price

News of an under-priced item tends to spread like wildfire. We’ve heard of cases where items have quickly sold out due to people sharing links that have them listed online at a price significantly under what it should be.

For instance, Next once listed a pair of sofas which should have been around £1,200 for an absolute steal at £98 – and when they did, it was shared across UK Deals sites and quickly capitalised on by seemingly-savvy consumers.

The customers who jumped on the deal were out of luck, though, because Next were not made to honour the incorrect price. Instead they simply cancelled the orders and refunded the customers – something which will often happen in cases like this.

If the shop is feeling generous, they may offer some sort of compensation (a discount voucher, for instance) to soften the blow, but that is completely at their own discretion.

Similarly, the idea that shop staff have to honour an incorrect price in-store is a commonly held misconception. In some cases they will do so as a courtesy; there’s no harm in asking and you may well get a bargain. However, they don’t have to make this offer, so if they refuse then there’s no point arguing back.

Items sold for the wrong price

Let’s go back to that last example and imagine that you’ve found an item in the store, taken it to the checkout and purchased it without anybody realising it is the wrong price.

In this case, the shop has no right to demand that you pay extra money: they have already sold you the item, and the mistake is on them. The only exception here is if you’d acknowledged what the correct price of the product should be before you bought it.

Parcels that you didn’t order

What do you do if a package arrives at your door one day, unsolicited? It’s easy to assume that since it has been sent to you it’s now yours, even if a shop delivered the items in error.

But in most situations this isn’t the case. A package that was sent to your address but meant for someone else needs to be returned, and the same is true if you receive multiple pieces of something that you did order.

The good news is that the company is at fault, and therefore it is their job to pay for any returns. You should get in touch with them and tell them that you can make the product available for collection. They may ask you to return it, which is fine so long as they cover any associated costs.