ROME, Nov 2 (Reuters) – Italy’s antitrust authority said on Thursday it had opened a probe into the way the country’s biggest lender Intesa Sanpaolo (ISP.MI) had started shifting thousands of customers to its new mobile-only service Isybank.

The investigation, which follows complaints by the main party in the ruling coalition and a warning from the central bank, highlights the digital challenge banks face as they strive to update their IT infrastructure and keep costs down.

Isybank, a cloud-based, low-cost mobile bank, is a key plank of Intesa CEO Carlo Messina’s long-term strategy to withstand competition from fintech, by focusing the bank on value-added services such as wealth management and insurance.

Italy’s competition watchdog took aim at how Intesa informed account holders they were being transferred to Isybank, adding it had received more than 2,000 complaints.

Intesa declined to comment.

Intesa informed customers with a digital message sent to customers’ online and mobile banking accounts, like any other message from the bank.

The regulator said the message was “ambiguous and sent in a way that is not consistent with the importance of the matter at stake.”

Many Intesa customers complained that, partly also because of the summer holidays, they had seen the notice only after the deadline to ask to remain with the traditional banking service had expired.

The absence of a written notice had already drawn criticism from the party of Prime Minister Giorgia Meloni, which asked the Treasury last month to give Intesa customers more time to opt out of what politicians described as a “forced migration”.

“The antistrust probe … is great news,” Letizia Giorgianni, an MP in Meloni’s Brothers of Italy party, said.

Complaints have also prompted Italy’s central bank to step in to monitor the transition.

After launching Isybank in June, Intesa at the beginning of October started moving about 300,000 customers. It is eventually targeting around 4 million clients who do not use its branch services.

The move, which entailed a change of bank details, temporarily disrupted some people’s accounts.

The antitrust said that the shift to Isybank carried with it “important changes” to the terms and conditions of the accounts, depriving customers of some services.

Intesa told a presentation in June that it would over time increase the number of services Isybank users can access on their accounts.

High-street banks’ current IT infrastructure is dated and often made unwieldy by mergers that brought together different systems, making the shift to the cloud extremely challenging.

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