The D.C. Public Service Commission yesterday said it was preparing a detailed public notice of hearings to mail to community groups and the City Council on a pending $56.3 million Chesapeake & Potomac Telephone Co. rate case.

The PSC action came on the heels of a citizens' group protest yesterday that both PSC and C&P public notices on the case were misleading because they did not spell out the size of the increase for residential customers.

"The commission is preparing a more detailed notice and that will be widely distributed for the April 9 and Aug. 15 public hearings," said PSC General Counsel Howard Davenport. "The notices will do a thorough comparison of existing and proposed rates."

Davenport said the public notice would be mailed to "all community groups, including advisory neighborhood commissions, other community organizations and all City Council members."

The North Cleveland Park and Forest Hills Advisory Neighborhood Commission, which acts as a liaison between city agencies and the neighborhood and represents some 12,000 citizens, demanded that public hearings on the case be postponed until both the PSC and C&P reissue more accurate and complete notices. The demand was contained in a letter mailed yesterday to the PSC, C&P, the City Council and 37 other advisory neighborhood commissions as well as Mayor Marion Barry.

The PSC said it would not postpone the hearings, now scheduled for March 2, April 9 and Aug. 15, but would run a newspaper ad about them. However, the PSC said it was considering whether to ask C&P to send out new bill inserts spelling out residential rate increases.

The phone company, which maintains it is under no obligation to specify the residential rate increase in its notices, has twice modified the original $78.5 million request. Under the original request, residential rates would rise by an average of 153 percent, while business rates would rise by only 12 percent.

The notice the PSC is mailing out is based on a $61 million rate request, instead of $56.3 million, Davenport said. The original $78.5 million request last August was first reduced to $61 million, then to the still lower figure. C&P must still present a new rate design proposal for the most recent adjustment in its request.

The PSC public notice reads, "A residential customer who now subscribes to unlimited metro calling or flat rate service can make an unlimited number of local calls for the flat rate of $12.49 per month. Under C&P's proposal, the same customer would pay $27.75 per month: $13.42 for dial tone service and $14.33 for usage." A sample of C&P's proposed rate structure is provided in the notice.

Davenport said the PSC is also making available by request charts on different types of residential service and is working on a chart comparing all classes of residential phone service in the District with Virginia and Maryland rates.