Rogelio Villarreal knew nothing about the French jeweler Cartier, he said, when an ad popped up on his Instagram feed last December. He clicked on it, perusing the pages of bling and other luxury items, including handbags, watches and necklaces, each listed for thousands of dollars.
Then Mr. Villareal, who lives in Mexico, noticed a pair of earrings: slender studded 18-carat rose-gold cuffs lined with diamonds, priced at just 237 Mexican pesos, or about $13.
He bought two pairs. Later, the price for the earrings was adjusted on the Cartier website to 237,000 pesos â more than $13,000.
The purchase initiated a monthslong tussle between the surgery resident from the northern state of Tamaulipas and the storied brand, with hundreds of social media users following along â some cheering, others taunting â and even a Mexican senator weighing in on the dispute.
âI was amazed to see how much the necklaces cost and so on and I said: âSomeday,â until I saw the earrings,â Mr. Villarreal, 27, wrote on social media. âI swear I broke out in a cold sweat.â
Within a week of the purchase, Mr. Villareal said, Cartier began a series of attempts to cancel the order, initially saying that the earrings were not available.
When Mr. Villarreal made no move to cancel the order, he started receiving phone calls from company representatives.
They told him that âthe earrings that I had ordered were not at the correct price, which is why they wanted to cancel the purchase, and that because of the inconvenience they would give me a gift,â he said.
As âcompensation,â the company then offered âa gesture from the house of Cartierâ â a complimentary bottle of Cartier CuvĂ©e champagne and a leather Cartier item, according to an email sent to Mr. Villarreal.
He decided to reject the gifts and fight back, using a contact form on the companyâs website to cite a federal consumer protection law in Mexico that says that a goods supplier can be taken to court âby not respecting the terms and conditions under whichâ a product or service is purchased.
Cartier has not responded to several requests for comment.
Mr. Villarreal found the terms and conditions for sales on Cartierâs website in Mexico, which state that any dispute could be brought to the Office of the Federal Prosecutor for the Consumer for âconciliation.â
So he did just that. He filed a complaint with the Matamoros branch of the federal consumer protection agency.
The agency, which has a role similar to that of the Federal Trade Commission in the United States, has a history of intervening on behalf of consumers when retailers change list prices after a sale.
In February, the consumer agency invited consumers to join a class-action lawsuit against Sony, which had canceled orders for a PlayStation 5 console that it had offered on its website in Mexico for a 30 percent discount.
The consumer protection law is so well known in Mexico that people use social media to draw attention to erroneous prices on Amazon and other retailersâ websites in posts that are widely seen and shared, according to El Economista, a newspaper in Mexico City that covers financial news.
Mr. Villarreal said that the consumer agency had summoned Cartier for arbitration and that the government had made several attempts to mediate an agreement. Agency officials said they could not share information about an open case with anyone other than the parties involved.
If the consumer protection agency finds that a company is at fault, it can impose fines or other penalties, but it canât force a company to abide by a price it listed, said Jorge LĂłpez Zozaya, a corporate lawyer in Mexico City. If no agreement is reached, either party can ask for a judge to resolve the complaint.
Mexican law does not extend protections to consumers if a listed price was clearly a mistake, Mr. Zozaya said.
âIf this case had gone to a court of law, it probably would have resolved favorably for Cartier,â Mr. Zozaya said.
But there appeared to be a truce in the matter. Ahead of a consumer agency mediation hearing next week, Mr. Villarreal said on Monday that he had received notice from Cartier that his order would be fulfilled. The agreement could not be confirmed with Cartier or the agency.
âWar is over,â he wrote in English in a social media post.
Some users applauded his tenaciousness in getting Cartier to comply with the terms of his purchase, while others, including a Mexican senator, accused him of abusing the consumer protection system for his own gain.
âIt is wrong to take advantage of a mistake to the detriment of another person,â wrote Lilly TĂ©llez, a senator from the state of Sonora, adding, âeven if the law supports you.â
Mr. Villarreal said that he was happy that the ordeal appeared to be over but that the legal process would continue until the earrings arrive.
Elda CantĂș contributed reporting from Mexico City.