Unpaid salary discoved in private audit?

My overseas contract suddenly ran out of money prior to the end of the contract date. Those affected employees were terminated and sent to their respective home of record. The company had lost control of the spending (burn-rate) causing the contract to end 3-4 months ahead of schedule. Upon termination a private audit was done by an accountant who found over 10k of salary unpaid (base salary was miscalculated by the employer). Those findings and all supporting documentation were submitted to the company who has yet to satisfy those finding and continues to drag out the process (over 2 months). In the interim the company offered a severance package that does not mention the audit or the funds that were owed as part of the audit. If one were to sign the severance package (has a definitive end date) does that vacate the finding of the audit. This has been dragging out over three months, far exceeding DoL requirements to pay employees within a "time certain". I have a communication log that has dozens of attempts to HR, payroll and various management positions over the past 3 months. The company in question has yet to respond in writing to the audit with their findings whilst simultaneously dribbling out small incremental "payments", not totaling the numbers provided them in the audit. This company is a huge DoD contractor (top 6) by revenue.