Germany’s top financial regulator is appointing a special monitor to Deutsche Bank to oversee the lender’s handling of consumer service problems at its Postbank unit, a blow to the reputation of the nation’s top bank.

The head of the regulator BaFin has termed as “unacceptable” the disruptions experienced in Postbank’s online offerings, the difficulty clients had in reaching its customer service and in long processing times.

The issue has been a setback for Deutsche Bank’s effort to restore credibility after fines for lapses in money laundering controls, raids by authorities and other penalties.

BaFin has already had in place a monitor at Deutsche to oversee money laundering controls since 2018.

“We are making progress in improving processing times at Postbank as part of the action plan agreed with BaFin,” Deutsche Bank said in a statement.

Deutsche began the acquisition of Postbank, with its millions of clients and roots in the country’s postal system, in 2008 during the global financial crisis but struggled for years to integrate it.

The bank said in July it had completed a final phase of the integration, but in September, BaFin in an unusual rebuke said it had seen “considerable disturbances” at Postbank.

In 2019, Deutsche, which ranks as one of the world’s most important banks, embarked on a four-year, nearly €9 billion turnaround plan after years of losses.

The effort helped restore profit, but the bank’s share price has languished.

Deutsche Bank’s chief executive Christian Sewing has said Deutsche had made mistakes on Postbank and that it had devoted hundreds of additional workers to tackle the issues.

“We have not lived up to our responsibility here – and now we have to work all the harder to fix the problems quickly and completely – and regain trust,” Sewing said last month.

BaFin said the special monitor would report back regularly.

“He will focus on ensuring that customer orders are processed within a reasonable period of time and that customer orders that have not yet been processed are handled quickly, BaFin said.

A Deutsche Bank spokesperson said dealing with the issues was of the “highest priority”.