A group representing a large cohort of Tim Hortons franchisees is threatening legal action against the coffee chain’s parent company after a computer virus knocked cash registers offline at an unconfirmed number of stores.

In a letter addressed to Restaurant Brands International CEO Daniel Schwartz, a lawyer representing the Great White North Franchisee Association (GWNFA) said there have been “significant losses as a result of the current attack” and insists a meeting be convened no later than Friday to discuss the ongoing situation.

“Should you refuse to meet with our clients to resolve this important problem, our clients shall unfortunately be left with no alternative but to pursue litigation,” GWNFA’s attorney Peter Proszanski wrote on Monday.

He claims impacted Tim Hortons locations have suffered store closures, lost employee wages, lost sales, and food spoilage as a direct result of the malware-infected point-of-sale terminals. Resolving the issue and compensating franchise owners for their losses without delay is “of the utmost importance,” he stated.

The fast-food giant told The Canadian Press it is working with an external vendor to address a virus causing intermittent cash register outages, and no consumer data or credit card information has been compromised.

The Globe and Mail reported that fewer than 100 restaurants were currently affected, and fewer than 10 were unable to operate their point-of-sale system. The malware first affected Tim Hortons’ point-of-sale terminals a week ago, according to a source who spoke to the Business News Network on the condition of anonymity.

The crashing cash registers follow a number of other clashes between some restaurant owners, Tim Hortons and Restaurant Brands over changes to employee pay due to Ontario’s minimum wage increases, expanding menu options, and corporate cost-cutting.

“The public relations debacle related to the minimum wage increase in Ontario is causing tremendous downward pressure on the value of the Tim Horton’s brand,” Proszanski wrote.

This latest misfortune struck during the company’s widely-popular “Roll Up the Rim” promotion, which has been beset with problems of its own this year. The company distributed a small batch of misprinted cups with no messages under the rim in Atlantic Canada and Alberta.

Adding to the sting of Restaurant Brands’ cost-cutting, sales at the coffee-and-doughnut chain sagged for a fifth straight quarter while the parent company outperformed expectations for its fourth quarter results earlier this month.

Proszanski stated that while Restaurant Brands has provided franchise owners with “partial answers” regarding its efforts to minimize downtime related to the virus, a number of serious questions have not been addressed. Among those: how the outage happened, when Restaurant Brands become aware of the risk, and will hardware manufacturer Panasonic, reimburse franchisees for their losses.

Frustration is brewing over the faulty cash registers, according to BNN’s source.

“The cash registers just plain don’t work,” the source said. “Many of the stores had to close totally. Some had to close their drive-thrus and have customers go into the stores to one or two working registers.”

Tim Hortons customer Ben Verret tweeted a photo of a customer-facing monitor displaying an error message at a Levis, Que location on Tuesday. The screen reads, “A recent hardware or software change might have caused this.”

Chaos at Tim Hortons. They use Windows XP. pic.twitter.com/WrkrNz1Fsb — Ben Verret ⚡ (@verretor) February 27, 2018

Tim Hortons did not respond to CTV’s requests for comment by publication time.

With a file from The Canadian Press