The victim was forced to live in squalid conditions and subjected to repeated abuse at the hands of Wixon, 56, who kept her captive in her home in Tewkesbury.
Wixon was convicted at Gloucester Crown Court of false imprisonment, requiring a person to perform forced or compulsory labour, and assault occasioning actual bodily harm.
She will be sentenced in March.
Mandy Wixon who kept a woman as a slave for 25 years. (Image: Gloucestershire Police / SWNS)
Neighbour Kiram, 33, witnessed the sustained abuse and said she repeatedly raised the alarm, but nothing was done.
Kiram said: “It was disgusting.
“I’m just so shocked it’s been in waiting for so long. I made phone calls for social services, nothing was ever done.
“Social services failed her massively. She was diagnosed with global development delay and obviously, a lot of other learning difficulties.
“You could tell that she was vulnerable.
“The hygiene was not there. It was like house of horrors.
“There were a few occasions where she’d come to the window, but that was years later.
“We didn’t think she was still there. The victim is thriving. She is doing really well.
“She’s like a completely different person.
“Nothing’s gonna stop her from progressing the way she has done.”
Wixon forced the woman to clean her home and subjected her to frequent violence, including forcing washing-up liquid down her throat and splashing bleach on her face.
Kiram said the last time social services had been contacted about the situation was in 2019.
One resident described Wixon as “filthy” and said: “You get families and you know that there’s something about them, but you don’t know what it is.
“I don’t know Amanda personally, really, but I know a few of her children.
“Why did none of them ever questioned why she was being treated to that way? Why were they never made to scrub the floors?”
Another neighbour expressed disbelief, saying Wixon always appeared “normal” and that they would greet each other in passing.
The case has shocked the community, raising questions about how abuse of this duration could have gone undetected.