Unable to withdraw from spouse's plan because of error by new employer

[Guest billvic]

My employer claims to have lost the health insurance enrollment form that I completed when I started a new job in Feb. They had me fill out a new enrollment form at the end of April. A few days later I received my insurance card with an effective date of March 17. The effective date was apparently back dated after my employer received the second enrollment form. I was planning to cancel health coverage that I have through my spouse's employer when I obtained my new coverage. Both employers agree that my new job is a qualifying event. Because I did not notify my spouse's employer within 30 days of the effective date they are saying that I will have to wait until the next open enrollment period to cancel. I did not receive proof of the effective date until about 35 days after the effective date. My new employer admits that losing the paperwork is the reason that it took so long for me to receive my insurance card and proof of the effective date. They apologize profusely but say that there is nothing they can do which will allow me to withdraw from my spouse's plan. Do I have any options?