The rollover of TCF Bank customers to Huntington Bank left some people without access to their debit cards and online banking this week.

The change began last Friday and was signaled well in advance by Huntington. But in the days since, customers have jammed the bank's help center and website with complaints about lost access to key banking services.

"I'm sure they tried hard to do this well, but they've simply failed," Jeremy Bond, a TCF customer in Mount Pleasant, Mich., said Wednesday. He was repeatedly denied access while trying to set up online accounts with Huntington.

Ohio-based Huntington closed on its merger with TCF Financial, one of Minnesota's largest banks, earlier this summer. A rebranding is being completed this month, most visible in sign changes at branches and at the University of Minnesota's football stadium, where TCF had naming rights.

For weeks, Huntington told customers to expect their accounts and online services to migrate in early October.

Consumer customers received welcome kits that walk through how to access their accounts step-by-step, said Randi Berris, Huntington's director of external communications, in an e-mail response to questions from the Star Tribune.

"We understand that this can be difficult for some to navigate and that's why we're seeing the increased call volume," she said. "We are working through those calls as quickly and efficiently as we can."

Bond said he was told by Huntington customer service representatives that high transaction volume was the reason he couldn't access his accounts. The bank advised him to try again at odd hours when online traffic volume would decrease, he said. But he still wasn't able to access his accounts after repeated attempts Tuesday night and early Wednesday.

By contrast, Bond said he encountered few troubles when Michigan-based Chemical Bank and Minnesota-based TCF united their customers accounts after a 2019 merger. "I feel like the transition I went through from Chemical Bank to TCF was seamless compared to this nightmare," he said.

Greg Ott of La Quinta, Calif., tried to view his home equity loan that been acquired by TCF and is now with Huntington this week. But he has been unable to log in and spent hours on the phone waiting for help. He was told to visit a Huntington branch, but there aren't any in his area. "They don't have a process to handle national customers," he said.

Besides online access issues, some customers who were told they could still use their TCF cards this past weekend found that their cards were declined.

The Huntington spokeswoman said the debit card issue that affected a small subset of TCF customers on Friday night and Saturday morning was resolved Saturday afternoon. "We sincerely apologize to our customers for the inconvenience," she said.

Matthew Koscielski of Bertha, Minn., said Wednesday that while he is now able to use his debit card for credit purchases, he still can't use it for debit transactions that some retailers require.

He learned of the problem Friday night after work when his card was declined at a gas station and a Burger King, and then saw social media posts from people experiencing similar issues. He wishes the company acknowledged the problem sooner. "They seem to not really have it all together," he said.