Frontier Communications is being accused of overcharging former Verizon customers by hundreds of dollars after purchasing broadband and DSL networks from the major telecommunications company.

According to a report from ABC Action News in Tampa Bay, Florida, Frontier Communications has struggled to maintain its internet services in Florida, resulting in long stretches of outages and monthly bills well beyond the advertised price.

The issue started when Frontier, a telecommunications company that operates in 29 states in the U.S., purchased wireline operations from Verizon in Florida, California and Texas. The transaction was completed in April 2016, at which time Frontier began operating the fiber optic broadband (known as FiOS) and DSL networks.

The transition has been particularly bumpy for residents of Florida formerly served by Verizon. According to the local ABC affiliate, Frontier has been overcharging customers, including small business owners, by hundreds of dollars.

In one instance, a customer purchasing phone and internet service was charged $340 on her first bill. The charge was supposed to be for only $100. Frontier promised to fix the mistake after the customer contacted the company’s company service. It instead began charging her “various amounts” over the course of several months without fully resolving the issue.

Another customer claimed her bill shot up by $260 per month without notification. The dramatic increase included a charge for a second cable box, which she did not have. After customer service failed to resolve the problem for her, she simply started to pay the charges.

That customer should not count on getting a refund for those funds, if an anecdote from a Frontier customer in California is to be believed. According to a CBS affiliate in Palm Springs, a 79-year-old man was charged $127.62 by Frontier after he canceled his service and was never granted a refund by the company.

The issues with Frontier have been widespread and ongoing. Shortly after the company took over the Verizon networks, Florida Attorney General Pam Bondi said her office received more than 120 complaints about the company. Those complaints ranged from extended outages of both phone and internet services to disruptions in land line connections and access to emergency services.

The telecommunications company has also come under fire in West Virginia for refusing to return more than $4.7 million in stimulus found that it received from state as part of a project to expand high-speed internet access. The federal government believes the state overpaid the company, which Frontier has refuted.

Consumers who have experienced issues with Frontier Communications are advised to notify the company in writing via certified mail, according to consumer protection attorney Alan Borden.

In a statement to ABC, Borden said the mailed letter “puts them on notice” that they’ve done something wrong. "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," he explained.