How can I get in contact with someone in payroll for City of Seattle?

I have left voice messages and emails every single day for Human Resources for City of Seattle to get a final check reissued for the past week. No response. My son found his last check dated from April and can’t deposit it because it’s over 6 months old. Both he and I have tried to reach a human being to no avail. We live in Portland or else I’d drive over to the main offices. Does anyone have any ideas?