This is within jurisdiction of your local small claims court, and while a lawyer may be of assistance they are barred from appearing in court in your defense:

File a complaint in your local small claims court, and serve the collection agency with notice of a suit. They will be compelled to appear in court with EVIDENCE of your debt, as well as you will be compelled to provide EVIDENCE that you have paid all debts for your uniforms.

I think this is probably "payroll deduct" uniform fees that the company failed to pass on to the employee. You'll need your paystubs showing deductions for uniforms and should be able to walk away.

In your complaint, be sure to file for court costs, administrative fees, and travel. If you make a copy, fax, or phone call keep detailed reciepts of all expenses involved in fighting this. I'm waiting for my phone call as well... but remember thinking some items were never charged to me. This is low down, dirty crap however as I've been gone over a year.