How can benefit refund be made when an employee's benefit program changes?

PS version 9.2 PT 8.59.15

Our HR department had employee who was in a benefitted program and then was transferred into a non-benefit program. Somehow the medical and dental deductions came out, perhaps it was the timing of the transfer. When it was realized a request came to reimburse. When I went to the payline and selected one-time deduction tab. I selected the plan type Medical, but when I went to select the Benefit Plan there is nothing to choose.