Stung by angry consumer complaints about poor service, an official of Arlington's MetroCable TV has announced plans to add 12 more phone lines and four more workers to take customer calls.

At a news conference last week, John D. Evans, president of Arlington Cable Partners, which operates as MetroCable, also predicted fewer problems with outages. A recent spate of outages was caused by bad weather, construction mishaps and a $4.5 million upgrade project to increase the number of channels on the cable system from 36 to 54, Evans said.

"We're on top of it. If there's an outage I'm personally called," Evans said. "We think we're through the worst of this."

Evans said the upgrade is ahead of schedule and should be finished by spring. About 2,000 customers in western Arlington started receiving seven additional channels last week. They include the Nashville Network, a Spanish language channel, two home shopping channels and the Christian Broadcasting Network.

Eleven more channels will be added next year, including three pay-for-view channels, Evans said. He added that 5 percent of money spent on purchases through the new fashion and travel shopping channels will go to county charities.

About 37,000 Arlington households are cable subscribers. According to MetroCable, the average subscriber has lost 606 minutes of programming during 112 outages so far this year. Last year, the average subscriber lost 482 minutes during 107 outages.

In August, the entire system went down with full service restored about 26 hours later. Cable officials said a construction crew working in the Virginia Square area may have severed a line.

Complaints to the county have quadrupled this year, from 68 complaints in 1986 to 279 so far in 1987, said Gary Smyth, Arlington's cable administrator. Smyth said the complaints are mainly about outages. The company generally responds to complaints within 24 hours, as required by the county, he said.

However, many customers say that they are unable to get through on the phone to register their complaints.

"They get a busy signal or a tape recording when they get {through}," Smyth said.

Arlington resident Bruce M. Isaacson is so frustrated with the cable system that he is organizing a petition drive.

He said he hopes to gather several thousand signatures to illustrate the high level of dissatisfaction among cable subscribers.

"I cannot remember one day in the past three months when we've had totally uninterrupted service," Isaacson said. "I would like service to equal the amount of money I'm paying." Isaacson also complained that MetroCable has not offered customers a rebate to compensate for the outages.

Subscribers pay $15.25 a month for basic service with additional fees for services such as Home Box Office.

Smyth said the county "is looking into every means available to make sure subscribers are served. If somebody came in with a petition, the county board would certainly be interested and want to respond."

But the county has no direct control over the privately owned cable system, Smyth said. The county's next review of the franchise agreement is not scheduled until 1992, he said. The county this spring extended MetroCable's franchise until the year 2000 contingent on the company completing the channel expansion. The company has been in service in Arlington for 12 years.

County Board Chairman Albert C. Eisenberg said the county could initiate proceedings to cancel MetroCable's franchise or impose fines for poor service but said he thought such penalties to be "rather harsh."

Cable president Evans said some of the outages are caused by the upgrade project. He compared the project to "trying to repair the highway while you're using it."

Some lines are turned off while crews work on the upgrade. Customers are notified in advance of these outages. No work is done during prime-time viewing hours, Evans said.

The company's policy is to give rebates if service is off continuously for more than 24 hours; customers must request the rebate. Asked if the company would give rebates to all customers to make up for the spate of outages this year, Evans said: "There are internal discussions but no change at this time in our policy."