President Reagan telephoned get-well wishes to William J. Schroeder yesterday and got an earful from the artificial-heart recipient, who said he was "getting a runaround" in his attempts to gain Social Security benefits.

"My problem is that I filed for Social Security in March of 19. . . ," Schroeder said, but Reagan interrupted him, saying he was "having trouble hearing you," and asked him to repeat his problem.

Schroeder did, and the president pledged to "get on it right away."

Reagan also praised Schroeder, 52, for his "remarkable recovery" since the Nov. 25 implant. "We're delighted that you are getting into shape to be able to leave the hospital," Reagan said.

A Social Security Administration spokesman said Schroeder was approved for disability benefits in October, but because he is a retired federal worker whose benefits are offset by his pension, his paperwork was sent for processing to the Office of Personnel Management. "We will do everything we can to get this processed as quickly as possible," Jim Brown said.

Tapes of the three-minute conversation were released here by Humana Hospital-Audubon. The White House issued an abbreviated version that included Reagan's get-well wishes but omitted Schroeder's side of the conversation.

A hospital spokesman said Schroeder also walked more yesterday and followed an exercise regimen to strengthen his limbs and neck.