MONTPELIER, Vt. (AP) – A day after its executives were grilled about customer service failures, FairPoint Communications said Thursday it would miss a deadline for responding to a complaint questioning its fitness to continue operating the region’s dominant telephone network.

The company, which had been given a Sept. 10 deadline to explain why it should be allowed to keep its Vermont certificate of public good, filed for and received a one-week extension for formally responding to a “show cause” petition filed July 14 by the state Department of Public Service.

“We want to make sure our response is as detailed and thorough as possible,” said spokeswoman Beth Fastiggi.

FairPoint, which is based in Charlotte, N.C., took over the landline and Internet business of Verizon Communications in Maine, New Hampshire on Vermont as part of a $2.3 billion deal.

But its customers have been plagued by problems – from billing mistakes to unanswered complaints to long waits for assistance on calls to a customer service center – and have deluged regulators with complaints.

On Wednesday, in a rare joint meeting of regulators from all three states, FairPoint executives said it would be two more months before it has a clear plan to resolve its customer service, billing and other problems.

CEO David Hauser said the company is making improvements, saying calls to a customer service center are now answered in 20 seconds or less more than 89 percent of the time. He said billing problems remain, and that about 22 percent of orders for new service or changes to existing services are late.

Preparation for that meeting – and the company’s probe of an anonymous e-mailer’s assertion that FairPoint faked its readiness to take over the network in testing last summer – apparently delayed FairPoint’s ability to respond to the Vermont petition.

“I know they devoted some rather intensive resources to the allegation about the pre-cutover testing,” said James Porter III, special counsel to the Department of Public Service. “That being said, we continue to be disappointed at their failure to address the service quality problems and we certainly hope they’re taking our petition seriously.”

In its petition, the Vermont Department of Public Service – which represents consumers – asked the state Public Service Board to examine whether FairPoint should be allowed to continue to operate in Vermont.

The response was due by the close of business Thursday, but it filed for the extension Wednesday in a one-paragraph letter from counsel Nancy Malmquist. Typically, such requests are granted, according to Porter.

Now, FairPoint has until Sept. 17 to respond. A status conference in the case is set for Sept. 30.

“This really doesn’t slow anything down,” said Fastiggi. “It still allows the docket to proceed.”