PHILADELPHIA -- An argument over service at a Philadelphia fast-food restaurant ended with a customer getting a lot more than she ordered.

A fast-food worker has lost her job and faces criminal charges for allegedly throwing hot grease on a customer.

Vouncile Lambert pulled up for a burger and fries at a pick-up window at a Checkers restaurant in West Philadelphia.

Instead, she left with second- and third-degree burns to her upper body.

Lambert blames a not-so-courteous clerk who had been fighting with a customer in front of her.

Lambert said the girl first dumped a soda on her, and as she spoke to a manager about the incident, the girl returned with hot oil.

"That's when the young lady came from behind with a cup of oil and just threw it through the pick-up window," Lambert said.

According to a police report, a relative of Lambert had spit on the worker.

An area manager for Checkers said the customers were upset when the employee closed the walk-up window on them Sunday afternoon.

Lambert, who was burned on her arms and chest, said her "skin was cooking."

A manager at Checkers said the 17-year-old clerk has been fired. She's also been charged with aggravated and simple assault, as well as reckless endangerment.