Why do I have to pay for their mistake?

I took out car insurance with OUTSURANCE about 4 months ago. The consultant assured me that my premium would be fixed for at least 12 months. Yesterday Outsurance Life called me to do a quote for life cover. It turned out when I took the car insurance policy the consultant captured my marital status as MARRIED. I have never been married ever! Due to this mistake and the fact that I am not married, they increased my car insurance premium by 21%. This is completely unacceptable. Now I have to pay more because of their mistake! If I had known they would charge me so much from the beginning, I would have shopped around further. And why on earth am I a higher risk profile if I am not married? Why am I being discriminated against?