40% increase in premium without any notification

Going to keep it short and sweet... Debit order for my insurance (2 vehicles, home contents and building insurance) goes off this morning and surprize surprize an almost 40% increase.... This without notifying me about this increase, just whoop R800 more on my premium... I call in, a lady tries to assist and promises to call me back, waited untill now and called in to cancel the policy. Am told I can not cancel with immediate effect, have to give 30 days notice... But they can take R800 more off of my account without any notice? I will be reversing the debit order, since I did not consent to ANY increase and the debit order is therefor unauthorized...