Cancelled in May still being billed and harassed

I cancelled my Tracker in May - was still billed end May and June for it. I eventually got that reimbursed.I have since emigrated to Canada and am getting harassed by them with their calls - which I do not answer because I will pay roaming. I get a rude e mail today saying if I don't contact them NOTHING will change. I was promised they had closed my account and cancelled the debit order.