When Stuart Frankel from Miami, Florida came up with a new idea to draw customers to his Subway restaurant, he had no idea what he was about to do for thrifty fast food lovers.

Frankel's idea to lower the price of his store's footlong subs to a round $5 was a hit with locals, and eventually spread to Subway chains across the country. But of course, it was too good to last, and by 2014 Subway had already raised the price of its footlongs back to $6.

Then, the sandwich prices crept up to $7 earlier this year.

Those changes coincided with a 25% drop in customer traffic, which left Subway worried as McDonald's and Taco Bell are revamping their value menus. Plus, other sandwich chains which launched their own value menus have been faring better than Subway.

To make it up to their customers, the chain announced that they're bringing back the $5 footlongs promotion for a limited run, starting in January 2018. But before you start celebrating, not everyone is so happy about the deal.

And the backlash is so serious it could make it difficult to get the deal at a Subway near you.

The problem is that the sandwich chain's franchise owners get to choose whether they opt in to the $5 footlong deal or not, and a lot of them aren't happy about the discount.

After feeling the pinch during the last few years, some Subway owner say the new promotion will hurt them more than it helps. Already, 400 Subway owners from across the country have filed a petition with Subway's head office protesting the deal.

"The national promotional focus over the past five years ... has decimated [us] and left many franchisees unprofitable and even insolvent," the petition read.

Subway owners want the chain to shake up the menu to attract new customers, and may refuse to go along with $5 footlongs if they believe it's not in their best interest.

So before you try to grab your favorite sandwich for a discount, you might want to check that your local Subway restaurant is even offering the promotion.

Consider yourself warned!