Legal: premium benefits being charged

My husband's company was bought out by another company. The company promised contracts for six months, saying they had work and urged my husband not to quit. Nevertheless, my husband was never worked. He finally quit and went to work for a different company. Today, I would say another 6 months later, we received a letter in the mail saying we owed close to 2k worth of premium benefits that were never deducted from my husband's paycheck. It seems unfair that we lost money by staying loyal to that company and now they are trying to take more money away. Can they do this?