On a recent trip to Portugal, I discovered a magical way to resolve a dispute that I wish more countries would adopt – and that I’d like more travellers to know about.

I was visiting friends who live in the Algarve and, while idly opening my banking app one evening, I was horrified to see I’d been overcharged more than €100 ($164) for a single can of Coke I’d bought the previous day. The drink should have cost €1.50, but the owner of the cafe where I bought it had in fact charged me €105. I assumed it must have been a simple mistake, a slip of the finger. I kicked myself for just tapping my phone on the card terminal without checking the amount; I was in a hurry. Not a mistake I’ll ever make again.

I rang my bank immediately to discover the payment couldn’t be stopped. The only form of action, said the call handler, was to return to the cafe and ask for a refund. She added that these “mistakes” were happening with increasing regularity in bars and restaurants around the world. And that many customers were being caught out by not checking before tapping.

When I returned the next morning, the cafe owner refused to refund me, shaking her head at the very idea that a mistake had been made, even after I showed her the evidence in a screenshot. Her grasp of English seemed to have worsened overnight, and I found myself getting increasingly exasperated.

I suggested we contact the police, but instead my friend Amber picked up a red, A4-sized booklet marked “Livro de Reclamacoes” from behind the cafe’s till. This magical item is Portugal’s complaints book – introduced 20 years ago to give consumers strength in just such a dispute. It’s an official and permanent form of redress that, under Portuguese law, must be held visible at every establishment supplying goods and services across the country, from hotels and campsites to restaurants and bars.

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The system allows any customer with an issue to publicly register a complaint about a business. One copy of the complaint is lodged with the country’s Economic and Food Safety Authority (ASAE), while another is kept by the complainant, and it also remains in the book for all to see (it is recommended you write in pen, for obvious reasons).

Similar to a bad Tripadvisor review – only far more official – it is also an administrative headache. Within 15 days of a complaint being made, the business is duty-bound to provide an explanation to the ASAE, which examines the evidence and decides how to proceed. While the Livro de Reclamacoes is now online too, a copy must be displayed and available for use in all physical businesses.

When Amber picked up the complaints book, the grumpy cafe owner acted immediately. Before we had so much as opened the first page, she reached for her wallet and swiftly handed over €100 without another word. I was still overcharged for my Coke, but €3.50 was an easy loss.

Just the threat of the Livro de Reclamacoes was enough to prompt action. What a marvellous system, I thought, but I do wonder why more people don’t seem to know about it. Amber and her husband, Paul, moved to Portugal three years ago and learnt about the Livro de Reclamacoes on a Facebook group for expats, but I’ve not spoken with anyone else who knows about it. The usual call-outs on social media to canvass opinions from friends and followers were met with silence – a first during any article research.

In 2017, the physical Livro de Reclamacoes was broadened to include an online service to reflect the growing number of online-only businesses. The website helpfully includes YouTube videos explaining how to make a complaint. And the system now includes any business offering goods and services, not just in the tourism sector. If a business has a physical premises, it must display a copy of the complaints book; if the business is only online, the electronic version can be used. One with both a physical and an online presence falls under both.

Peru has a similarly named and operated system with a 15-day time frame for business owners, as does Spain, whose version is called the Libro de Hojas de Reclamaciones. Spain’s book also consists of triplicate forms – one copy for the consumer, one for the business owner and one that must be taken by the client/consumer to the local consumer office, the Oficina Municipal de Información al Consumidor – but it is even lesser known than Portugal’s version, and the advice on how to use it is buried on Spain’s Citizens Advice Bureau website.

In a charming move, Portugal also offers customers an official way of thanking businesses for outstanding service, with an online compliments book, the Livro de Elogios. By the looks of its paltry number of followers on social media, however, take-up of that doesn’t seem as robust as that of the complaints book.

The Telegraph, London