The ineffective regulation of those practising talking therapies - such as counselling and psychotherapy - is leaving patients at risk of harm, the BBC's Victoria Derbyshire programme has been told.
For two sexual abuse victims, painful memories were brought back to the surface.
Sitting in a room with three female counsellors, "Marie" hoped her counselling would help her deal with at least some of the emotional pain caused by the sexual abuse she had endured from the age of nine to 18.
They had begun by saying "all the right things", she explains.
But looking back on the session now, she feels like she had been in a "place of terror".
The main practitioner sat so close, she says, that she was able to feel their breath - reigniting memories of past sexual assaults.
"It was very intimidating, my space being invaded," says Marie.
When she repeatedly sat with her legs crossed, contrary to the therapist's orders, she says the counsellor "actually got hold of me, holding my arms, looking in my eyes".
"I was getting very, very distressed, and feeling very sick, very ill, shaking.
"It's at that point they actually brought a sick bowl in because I was so distressed and traumatised."
The therapists later asked her if she wanted to be given a bath by all three of them, "as a way of showing nurturing towards me", she says.
'Slap on wrist'
The government has recently begun a consultation into the regulation of healthcare professionals, calling for an improved system "to protect patients".
"While the healthcare regulators are generally effective in protecting the public from serious harm," the Department of Health says in the foreword, "there has been criticism, not least from the regulators themselves, that the system is slow, expensive, complicated, reactive, overly adversarial and confusing for patients, professionals and employers."
The main therapist was suspended following a hearing after Marie made complaints against her.
But after an appeal process - which Marie was not allowed to attend - this was withdrawn, and she was allowed to continue to practise.
"It's appalling, it's disgraceful," she says. "They've caused me so much harm and yet the sanctions they give - it's like a slap on the wrist.
"Most therapists are ethical, but the ones that aren't - there's no deterrent."
In a 2016 report, campaign group Unsafe Spaces said "at least one in four" of those struck off appeared to still be practising.
'He wanted me for sex'
As a child, Kate was sexually, physically and emotionally abused.
She sought professional help through the NHS years later as an adult, each week meeting a psychotherapist who knew she had a long history of mental health problems because of her traumatic childhood.
Yet she says he too sexually abused her. "The person who was supposed to help me recover did no more than perpetuate the abuse."
In 2010 he pressured her into having sex with him, she says, which continued for three months.
"I was terrified but I didn't have the strength to stop it. It took me back to the abuse I had suffered as a child.
"I thought he cared about me but all he wanted me for was sex."
When Kate finally found the strength to report him, he was immediately suspended by the NHS Trust and sacked for gross professional misconduct. Kate was paid damages.
Two years later she decided to go to the police, who investigated. But prosecutors decided not to take the case to court, leaving Kate devastated.
"Victims of sexual abuse in childhood who suffer severe mental health problems in adult life should be able to receive treatment from NHS services without being abused again. The law is in place and should be used," she says.
Kate says that after her psychotherapist was sacked, he was still able to work privately.
Gary Fereday, chief executive of the British Psychoanalytic Council, says the current regulatory system "allows unscrupulous people to claim they're psychotherapists".
"If they've been struck off from one register they can simply register with another body, or call themselves something different, and continue to practise."
The Department of Health said it had created "a comprehensive public record of accredited professionals, overseen by the independent Professional Standards Authority."
Marie now wants to make sure no-one else has to go through what she did.
"I think it would break most people. And they've been broken once - that's why they're going into therapy."
Watch the Victoria Derbyshire programme on weekdays between 09:00 and 11:00 on BBC Two and the BBC News Channel.