cancelled ins still debiting acc

I had a vehicle insurance with Hollard, i cancelled on the 2 December 2014 giving a months notice, at the end of Dec 2014 they proceeded to deduct of my account, i only had a mail from Hollard in the 2nd week of Jan2015, i still qeuried how could they only reply to me a month and half later. hollard has now once again deducted this double transaction of my bank account. This has rejected and now i am stuck with the bank charges. I am very dissapointed. I followed normal way of cancelling and no one @ Hollard contacts me.