Frontier Communications' purchase of FiOS and DSL networks from Verizon last year led to immediate problems for customers that took weeks to resolve.

More than a year later, some ex-Verizon customers in Florida say they are still having major problems with their new provider.

"Some say Frontier Communications has overcharged them hundreds of dollars and have struggled to get a satisfactory response from customer service," a report by ABC Action News in Tampa Bay said last week.

Frontier bought Verizon's wireline operations in Florida, California, and Texas, taking over the networks in April 2016. In Florida, the transition was followed by weeks-long outages, painfully long customer-service phone calls, and big early termination fees, state Attorney General Pam Bondi said at the time.

$100 bill becomes $340

In the latest report, ABC quoted Frontier customer and small-business owner Danielle Ferrari as saying that Frontier charged her $340 for her first phone and Internet bill when it should have been about $100. Frontier promised to fix the mistake when Ferrari called customer service, but the company continued overcharging her by "various amounts" for months, the report said.

Another customer named Christina Herrman said that her bill surprisingly went up to $260 a month, including a charge for a second cable box that she did not have.

"She said she repeatedly tried to call Frontier to clear up the overcharges but struggled to find a resolution with customer service," the ABC report said. "She said she got so frustrated she just gave up and started paying the charges."

In all, ABC notified Frontier of three customers with problems, and the company told ABC that it is working to fix them.

In California, a local news station reported that a 79-year-old man says Frontier never refunded him for an overpayment of $127.62 after he canceled his service. Stop the Cap has a roundup of these stories.

Overcharged consumers can take action

Frontier customer service can be reached by phone at 1-800-921-8101 or online. But overcharged customers who get no results from customer service should consider notifying Frontier of the problems in writing, preferably by certified mail, consumer protection attorney Alan Borden told ABC.

"That puts them on notice that they've done something wrong," Borden told the news site. "At that point, when it goes month after month after month that they're not clearing that charge up or haven't responded in an adequate way, that's when you have the right to sue."

Customers can also file complaints with the state government's consumer services department or with Attorney General Bondi.

We contacted Frontier today and will update this story if we get more information.

Last year, Frontier said that many of its post-acquisition problems stemmed from corrupt data in Verizon systems, but the company said it had figured out how to fix them.

Frontier is also embroiled in controversy in West Virginia, where it is refusing to return $4.7 million in stimulus funds "that the federal government says West Virginia overpaid the company as part of a statewide project to expand high-speed Internet," the Charleston Gazette-Mail reported.