I have a home loan withe Standard Bank

I have a home loan withe Standard Bank. I have been using them as my home building insurer as well, I have secured a better offer somewhere else, however; Standard Bank would not let me go...I have sent them every piece of information of my new insurer, but still they take long to respond to me emails and when they respond they ask for something else. They said they can review my policy with them, but the circle continues