Standard Bank not stopping exorbitant insurance premiums on home loan

I have a home loan with Standard Bank. There was a Standard Bank Insurance life policy associated with the home loan. However, the premium suddenly more than doubled without prior notice thereof to me. I lodged a complaint asking how the risk suddenly doubled, but receive a totally vague and unsatisfactory response from Standard Bank. I then proceeded to arrange my own insurance, and provided proof of this to Standard Bank in writing, I also requested that they stop deducting the gouging, exorbitant premiums because I had arranged alternative insurance. Yet, in spite of this, they are STILL gouging me by debiting the exorbitant premium from my bond. This is ******* and I demand an IMMEDIATE and FULL refund, PLUS interest, of ALL premiums *******ly deducted.