The girl, identified as Rosa-Maria J., came to Germany from her poverty-stricken home village aged just 18 on the promise of a steady job for the millionaires in their fancy villa, kitted out with a sauna and swimming pool.
State prosecutors have begun an investigation on suspicion of "exploitative human trafficking," though a judge has suggested a settlement of €20,000.
Now 21, Rosa-Maria J. told the Hamburger Morgenpost newspaper, “The family promised me $800 a month for my work as household help and children's nanny.”
But the couple – a 43-year-old German man and a 41-year-old Ecuadorean woman - took the girl's passport on arrival, banned her from making any contact with the outside world and refused to pay her.
"I had to work every day of the week, sometimes 14 hours a day," she said.
"I got long lists of household tasks that I had to work through," she said, before adding that the wife constantly kept tabs on her.
"I felt like a slave."
She was also not allowed to eat with the family, or even to eat the same food. Instead, she had to prepare her own simple meals and eat them alone after the others had finished.
Penniless, unable to speak German, and knowing not a single soul in the country, Rosa-Maria J. did not know what to do. "I used to sneak out of the house at night and sit in the woods crying," she told the paper.
Whenever she asked for her pay, she was told to work off her two-year contract first.
The real-life Cinderella finally found her fairy godmother in the form of a Colombian woman working in a discount supermarket – but rather than a prince's ball, Rosa-Maria J. ended up in court suing the couple who had mistreated her.
Each Saturday she was taken to a nearby discount supermarket, given a small amount of money, and sent shopping for food – and picked up afterwards. There, Rosa-Maria J. made friends with a Colombian cashier.
Eventually she ran away from the house one night and took refuge with the cashier. She was eventually taken in by a human rights organization.
State prosecutors have already searched the house and the man's business. A court case has been scheduled for June, after the couple refused to pay the judge's suggested settlement of €20,000. They have offered €15,000.
The girl's lawyer's told the paper, "My client deserves to get four times as much."