It’s known for its Slurpees and Big Gulps, but over the years, 7-Eleven has also put its logo on frozen pizza, foam cups, laundry detergent and hundreds of other products.

Customers don’t always choose these so-called private-label items, even though they are usually cheaper than competing products from companies like Nestlé and Gatorade. Franchisees who run nearly all of the 9,100 7-Eleven stores in the United States must stock the items anyway.

At their annual convention in Kissimmee, Fla., last week, the franchisees cited the private-label items as just one way the company had made it hard for them to make money. They also criticized 7-Eleven for forcing a new contract on them that they said aggravated broader tensions over the suppliers they must use and how much they have to pay for the goods they sell in their stores.

“It’s no longer, ‘You make a dollar, we make a dollar,’” said Michael Jorgensen, the owner of three 7-Eleven stores in the area of St. Petersburg, Fla., and executive vice chairman of the National Coalition of Associations of 7-Eleven Franchisees. “The alignment of interests for 7-Eleven has changed.”