Do I have to repay an overpayment of benefits?

I was awarded disability for multiple health issues. When I finally received my first check I called the insurance company asking if they were sure the amount was correct. They assured me multiple times it was. After several more conversations with the assurance the amount was correct I started paying bills and using the money. I received my annual ss adjustment and notified the insurance company and now they come back and say I have been overpaid a substantial amount. This past year they corrected the monthly amount and applied the difference to what they said is the amount overpaid. My benefits have now been exhausted and they want me to send $27,000 plus dollars to pay the balance. I asked multiple times if the amount was correct and continuously told it was. The total of my social security and the amount of disability was less than my actual salary so I thought I guess they are right. Why do I have to repay benefits while I filled in my paperwork correctly and called multiple times and questioned it and they are the ones who made the error. Do I have a case against the insurance company? And what if I don’t have the money to pay this amount. Please advise.