Online banking services were restored to thousands of SunTrust customers Tuesday following a two- day outage.

"We have restored digital capabilities, although some have intermittent access," said Sue Mallino, a spokeswoman for the Atlanta-based bank. "We continue to monitor performance."

The crash occurred Sunday morning during a normal upgrade of the bank's online technologies.

Malliano attributed the disruption to “technical difficulty,” adding the problem was not related to Hurricane Florence, which was pounding the coast and flooding much of North Carolina at the time. Nor was it due to “any known cyber issue.”

VIDEO: In other SunTrust news

How local leaders say the development has made dollars and sense.

Earlier this year, SunTrust announced an employee had accessed information about 1.5 million accounts without authorization.

Bank officials said Tuesday that SunTrust is automatically refunding all ATM fees and other surcharges for use of non-SunTrust teller machines during the time when the system was down.

SunTrust also will refund customers for overdraft and late fees related to delayed transactions and payments during that time, but customers may need to request the refunds, the bank said.

While SunTrust declined to say how many customers use the web or mobile phone to access accounts, the general use of remote access has been increasing.

Though online access was unavailable, customers were still able to go to branch offices or use automated teller machines.

“We apologize to our clients and recognize the frustration this has caused,” said Mallino.

For several days, customers have vented their frustration and anger on social media.

“Going on two days with online access to @SunTrust still down,” wrote one Twitter user. “The fact that they can’t roll back a ‘normal system upgrade’ doesn’t give me warm fuzzies about their tech team’s ability to safeguard my information.”

A number of others said they were customers of SunTrust, but did not plan to be for very long.

Yet SunTrust’s tech woes are not unique in banking.

Just this year, there have been similar glitches at Capital One, TD Bank, BB&T and Citizens Financial Group, according to American Banker.

In February, TD Bank customers were unable to digitally access their accounts for more than a week after an "upgrade," American Banker reported.