CA Calling work. Wont ID themself.

Hello. I am on SS disability. I have not worked in over 10 years. My student loans are over 17 years old and I thought the SOL had long since run out and I didn't have to live in fear of the CA's anymore, but I guess I was very wrong. My husband just received a call at work. The man was very rude and demanded to know my maiden name, my address, and where I worked. When my husband asked who was asking, he was told they didn't have to give that info. My husband told them this was not his debt, it was none of his business and that they were not to call him at work anymore. The man said ok and to have me call this number 866-746-4853. I tried to look it up through Whocalled but there is no info. I want to write a letter telling them to stop calling, but I cannot find out where to send it. I'm scared to death to call for fear that somehow it will reactivate the debt and the nightmare will start all over again. I wish I could afford to somehow pay the forty thousand back, but I only receive 744.00 a month. If my husband looses his job because of the calls we will loose our health insurance and could not afford the $1,200.00 a month my prescriptions cost. I can't blieve this is starting again. I'm so upset. If anyone recognizes that number please let me know who this is. Thanks so much for any help with this matter.