Portable life policy

How can a company just cancel my life policy without notice and just keep all the monies paid in? I had a life policy at work where I paid 100% of the premiums. 105.00 a month. This was a policy that I could take with me at the same rate when I left the company. I had the policy for 17 moths before I retired. When I left I asked for info on how to make premium payments and was told I would get info in the mail. Never got any info. After a month and numerous phone calls to my former employer, was told that Anum Ins. Co had cancelled plan 2 months before I left due to lack of participation. So now I am out over 1700.00 and no ins for myself or my wife. After 2 more months of calls they reimbursed me 254.00 for premiums paid after policy was cancelled. How can Unum just cancel and keep all the money like that?