Reliance Standard is seeking reimbursement for alternative benefits they are falsely claiming I received.

My employer has a auxiliary group policy with Reliance Standard for disabilities. Our primary health insurance is through our Union with our Employer paying the premiums per our contract. Recently I was off from work due to several medical problems and I have just returned to this month. During my recovery period Reliance Standard after it’s usual excruciating processing time sent me a disability check. Even though I had filed no Social Security claim, Reliance had deducted an offset for Social Security. I called Reliance to no avail. The offset stood. Then I received a call from Reliance informing me that when I returned to work if I supplied the release documents from my Doctors then possibly I might receive part of the offset money if approved by them. Then, unexpectedly, the other day I received a second call from Reliance informing me that if I could supply additionally a statement from the SSA that I had no Social Security claim that I would receive the offset money in return. All this information was sent to them last Friday. Today, Saturday, I received a lengthy letter from Reliance informing me that I was receiving a “pension” in addition to Social Security and that the disability check they sent me should have been a considerably smaller amount. I am receiving no “pension” from anyone and am not receiving anything from the SSA. I did receive disability checks from the Union and SURS Disability Insurance, but from no other entities. Now, Reliance says it over-payed me $2,200 and wants reimbursement in 15 days. My Union Disability money ran out at about the time Reliance sent me their check, so the money from Reliance went to pay bills, living expenses and and co-pays from medical expenses. In this situation do I have any recourse or should I seek legal counsel?