Baristas at an experimental Starbucks-Amazon Go store in New York say the tie-up between the coffee chain and e-commerce giant has doubled their workload with no additional pay.

Some 30 Starbucks Corp. employees at the Times Square location will decide December 15 whether to join Starbucks Workers United, which has already unionized hundreds of cafes in cities around the U.S. Amazon.com Inc. itself has been roiled by labor activism at its warehouses, but this is the first time workers have sought to hold a union election at one of its retail locations.

The two companies launched the pilot partnership last year, with the aim of using Amazon’s cashierless technology and Starbucks’ mobile ordering to facilitate a fast and convenient experience for customers. There are now two “Starbucks Pickup with Amazon Go” stores, the one near Times Square and another on Manhattan’s east side.

The locations are divided into three sections: a Starbucks waiting area, Amazon Go market and a lounge. The idea is for people to pick up a coffee ordered from the Starbucks app, grab food from the Amazon Go and then walk out without having to stand in line.

“At the beginning I realized, ‘Oh, we don’t get paid extra for this Amazon work,’” said one barista, who requested anonymity to avoid possible retaliation from their manager. “There’s a whole plethora of new work that has to be done.”

Employees at the Times Square location joined colleagues at more than 100 Starbucks cafes who went on strike in November. The union has organized campaigns nationwide, with more than 250 successful store elections, though momentum has slowed in recent months. Amazon warehouse workers in Staten Island voted to join the Amazon Labor Union in April but the union lost two subsequent elections.

“From the beginning, we’ve been clear in our belief that we are better together as partners, without a union between us, and that conviction has not changed,” a Starbucks spokesperson said in an email. Amazon declined to comment.

The two Seattle-based companies have branded the pilot stores as effortless and contactless convenience. Yet some employees say the concept has been anything but effortless.

“Half of our customers come in and leave because they don’t even understand or comprehend what this is,” the barista said.

One Starbucks worker stands near the entrance to serve as a concierge, directing people to the coffee line or Amazon Go.

Starbucks workers stock Amazon inventory, such as prepared hot foods in the morning, which they say is a safety hazard. Employees claim they have been mildly burned while heating up Amazon foods. Management’s only response was to provide ointment, they said.

Employees also clean both the Starbucks and Amazon areas. Amazon representatives worked frequently in the store when it first opened, but now only come in a couple of times a week to check on the technology, the workers said.

Employees, who filed for the union election in October, say the difficult nature of the job, compared with working at a regular Starbucks, has fueled high turnover.