BILLED FOR AN ITEM THAT NO LONGER EXISTS

I put in a claim for lost jewellery item in December 2014, the claim was paid out in January 2015. I was advised that the billing would stop until a new item was registered, however Outsurance has continued to debit my account for the past four months. I have not registered a new item with them so I fail to understand what the monthly debits are for. I have attempted to call the call centre and have been sent from pillar to post with no resolution !!! I need to be refunded my monthly contributions as the item in question no longer exists !!!