disability

You must get an address and send a Cease and Desist letter to them CMRRR

I guess you're pointing at the West asset Collection services. There are certain things I'd like to inform you about a Cease and desist letter.
With a Cease and desist letter you clearly state your wish to deal with your original creditor instead of a collection agency. You also make it clear that the CA must stop all collection efforts from their side failing which they'd face legal proceedings under the consumer protection laws. Here's a sample Cease and desist letter for you.

What are they collecting on? West Asset is a student loan collection vendor for federal loans and they CAN garnish disability.

West Asset also collects on medicals too.

And if it is a student loan -

• Your student loan may be discharged (forgiven) if you become totally and permanently disabled. If a physician (doctor of medicine or osteopathy) certifies that you are totally and permanently disabled and you meet other requirements during a three-year conditional discharge period, your
  loan(s) may be discharged. This disability standard may differ from disability standards used by other federal agencies (for example, the Social Security Administration) or state agencies. Except as noted below for certain veterans, a disability determination by another federal or state agency does not establish your eligibility for this discharge.
  
• You do not qualify for discharge if the medical condition or impairment existed at the time you applied for the loan, unless after that time, the condition significantly deteriorated and then you became totally and permanently disabled. In other words, an individual who was already totally and permanently disabled when he or she applied for a loan cannot have that loan discharged for that condition.
  
• If you are a veteran, you will be considered totally and permanently disabled for the purposes of this discharge if you provide documentation from the U.S. Department of Veterans Affairs showing that you have been determined to be unemployable due to a service-connected condition. If you provide this documentation, you are not required to have a doctor complete Section 4 of this form or provide any additional documentation related to your disabling condition. Veterans who qualify under this standard are eligible for immediate discharge and are not subject to the standard discharge process that entails a three-year conditional discharge period.