TRIBECA — Disabled athlete Helene Hines defied medical experts by running dozens of marathons despite being told she couldn't walk, yet one of her biggest challenges is something much less grueling — buying a turkey sandwich in a TriBeCa deli.

The 65-year-old, who was diagnosed with multiple sclerosis 35 years ago, went into the store with her service dog, a black lab named Charlie, to grab lunch Wednesday.

Instead, she was hit by a tirade from workers at the TriBeCa Deli at 368 Greenwich St. who yelled at her to get out.

"The guys started yelling, "Get out! Get out!" said Hines of two cashiers who confronted her when she walked in.

"They said there's food in there [and they] cannot have hair from the dog."

Hines, a Long Islander who advocates for people with disabilities and once ran alongside President Bill Clinton to celebrate the Americans with Disabilities Act, said she tried to reason with the workers.

She offered to show them papers for Charlie, who wears a bright red vest with the words "service animal" written on it, but they would not look at them.

"I'm not going anywhere. Give me my sandwich," she said she finally demanded, telling the workers she was going to call 911.

Hines got her sandwich, walked outside and called the police.

"The squad car came and they went inside and told the guys the law," she said.

Hines — who has run 27 marathons and taken part in about another 20 with a hand-cranked wheelchair, winning the women's handcycle division in the 2010 New York City marathon — said she intends to file a civil lawsuit against the deli.

An assistant manager confirmed workers told Hines she couldn't bring Charlie inside, based on concerns he would contaminate the food.

"The cashier told her you're not supposed to bring the dog inside," he said over the phone Wednesday. "The place was busy."

The assistant manager, who declined to give his name, downplayed the incident, saying Hines got the sandwich she ordered. He added that the police came in and briefly talked with the workers.

Even after being informed of the rules by police, the assistant manager still appeared to be in the dark about the law — in what advocates say is just one example of chronic ignorance about service animals in local businesses.

The city's Health Department has made the law very clear, issuing a memo last year notifying businesses that they are violating city, state and federal rules if they bar disabled people with service dogs from entering.

"It is deemed discriminatory and, therefore, unlawful to deny a person access to a place of public accommodation, such as a restaurant or other food service establishment, solely because that person has a disability and is accompanied by a guide dog, hearing dog or service dog," city officials wrote in the May 2012 memo.

Business owners are also not allowed to demand paperwork showing that a dog is a service animal or that a person is disabled, officials said.

"A person with a disability accompanied by a service dog is not required by law to show proof or confirmation to you that they have a disability or that the animal accompanying him or her was trained to be a service animal," the city said.

Hines is a well-known and outspoken disabilities advocate who was told more than 30 years ago that she would never walk again, and used her determination as fuel to not only walk but run marathons.

She is an active member of Achilles International, which unites able-bodied and disabled runners, and won first place in the women's hand-crank wheelchair division of the group's first marathon in 2001. A longtime physical education instructor, she has also worked with disabled athletes on swimming and handcycling, and she recently published a memoir.

On Wednesday afternoon, Hines had stopped in the deli while waiting for her daughter — who suffers from a neurological disorder and also uses a service dog — to finish a doctor's appointment nearby.

When the situation at the deli was finally resolved, Hines headed back to the doctor's office on Hudson Street, only to find out her opera singer daughter, Jennifer Hines, 40, had just gone through a similar ordeal.

When Jennifer walked into the office, the receptionist told her she couldn't bring her dog inside.

"She's humiliated," Helene Hines said. "It's just not nice."

Her daughter was on the verge of leaving when the doctor finally came out to intervene.

"It's a very frustrating thing," Hines said. "You'd think in this day and age people would understand and be more compassionate."

With reporting by Irene Plagianos, Julie Shapiro and BMR Breaking News.