Billing for items not ordered!

I received email notification for an order for an Ipad Air I had not placed. I rang the "Customer Care Line" to advise that I have not made the order & that there was a serious error. Either the company have made a mistake in sending this to the wrong person or my account is being used by someone else.

I was assured by the person I spoke to that this would be dealt with straight away, the order cancelled & I would receive an email confirming this. I have not as yet received a confirmation email. This order is still showing on my account, including a balance to pay of £623.99. I rang the “Care Line” again but the person I spoke to cut the phone off whilst I was still speaking. I re-rang & requested to speak to the Complaints Department & the same person advised me that she could not put me through as they were busy. She stated the Complaints Dept would ring me back. This hasn't happened. I have also emailed the "Care Line", but have not received a reply.

I am waiting to see if they send me an invoice now. Any advice in the mean time very much appreciated