Cancellation Of Policy

I run a private ambulance service and have been insured with outsurance from 2013.In December last year Outsurance has decided to cancel my policy for my vehicles without giving me a proper feedback.I just received a letter stating that as of 19/01/2018 my policy will be cancelled.There have been claims on my policy due to accidents that have occurred and these accidents are beyond my control.Outsurance has initially insured my vehicles taking into consideration that it is an emergency service but now they did not even give me any other options but have decided to cancel my entire policy without giving me proper written feedback as to why it's been cancelled.I have sent them emails and have even called but to no avail.This is very bad service from Outsurance because they were quiet content on taking out large premiums from my account but when it came to claims they always have a problem.There are still refunds that they are also owing.