What is the process of inter-religion court marriage?

I am 30 year old, belong to Christian community, wants to get married under special marriage act. My partner is 27 year old, belong to Muslim community. I live in Delhi, my partner's address is from Kolkata. I called your helpline number and spoke to your representative. She told me due to some ban on conversion law, we cannot get married. Our families doesn't force us to follow a particular religion, our families agree and already talked with each other. We are now trying to find a legal way to get married and protected under laws. Your representative told me it cannot happen, I don't believe it at all. There must be a way. Please let me know.