The expert called in by the competition regulator to root out a bullying scandal has condemned its handling of the investigation after she allegedly faced obstructive witnesses and threats to its independence.

Alison White said she was “concerned and frustrated” about “the collective amnesia, obfuscation and wish to communicate through lawyers” of executives at the Open Banking Implementation Entity (Obie), an organisation set up by the Competition and Markets Authority (CMA).

In a scathing 10-page letter to the chairman of the CMA and the chairman of the Treasury select committee, dated 6 January and seen by The Telegraph, Ms White listed a host of grievances, including that she feels she has been sidelined since submitting her final report in August.

Ms White, a corporate governance specialist, was brought in to lead a committee examining allegations of wrongdoing at Obie. It was set up in 2016 in a state-backed effort to increase competition in banking by making it easier for startups to access customer data.

Her report found that a culture of bullying and intimidation existed at the unit, leading to the departure of its former boss in October.

However, in her letter this month, Ms White said she had become concerned that the process set up to address further complaints and offer whistleblowers potential redress lacks independence. The CMA and Obie reject this claim.

Obie has hired City law firm Eversheds Sutherland to handle internal complaints and the compensation process since Charlotte Crosswell, a former fintech boss, took over as trustee in October.

But Ms White said: “Consultants appointed and paid for by Obie and working to terms of reference set by Obie, can never have the independence that this situation requires.”

She said she was forced to prepare her report alone after a CMA director sitting on her committee, “caused considerable damage to the independence of his role” by endorsing a LinkedIn post by the Obie trustee at the centre of the scandal.

The letter will raise further questions about the CMA’s handling of misconduct.

Last month, the Telegraph revealed that the watchdog launched an internal investigation into claims another director pressured a whistleblower to retract allegations of misconduct at Obie. That investigation is ongoing.

Ms White said she contacted Jonathan Scott,  chairman of the CMA, and “raised concerns about the quality of the evidence provided to the investigation by a member of the CMA staff about their role in handling the complaints of a whistleblower”.

Ms White also complained that the investigation took “far longer” to complete than it should have done and cost more than £1m when it was supposed to cost less than £100,000. It was paid for by the nine banks that fund Obie.

She also said was left “concerned and frustrated” about “the collective amnesia, obfuscation and wish to communicate through lawyers” of Obie witnesses, adding that the communication process managed by the CMA “left a lot to be desired”.

A CMA spokesman said: “While we are grateful to Alison White for her independent report, we disagree with many aspects of her recent letter, some of which appear to be based on erroneous assumptions. This is partly because she has not been directly involved in the actions taken at [Obie] since her report was completed.

“As is typical for independent investigations of this nature, Ms White’s role has now concluded and it is for the CMA, [Obie] and the relevant banks to implement her recommendations.”

“The CMA has acted with even handedness, openness and integrity throughout this process and believe our actions clearly demonstrate that.” 

Ms Crosswell, the trustee of Obie, said: “We thank Alison White for her report last year and have taken the findings extremely seriously and are acting on her recommendations. We have undertaken major changes to our governance structure and continue to improve our day to day operations in line with best practice.

“We have established a robust redress process for individual complainants to raise concerns and appointed Eversheds to provide that process through a competitive tender. The complaints process is overseen by an independent non-executive director.”

Ms White declined to comment.