Can't cancel expired contract

I am living abroad and unable to call the usual numbers to stop my contract which expired in August, but for which vodacom still charges me monthly, in fact an even higher amount. I emailed them at the vodacom4u automatic email telling them that I am abroad. Ursula gets back to me and gives me a local number to call. So how does that help me? I then find a way to call using Skype, but after holding and entering my number I get told by an automated voice that I have exceeded the amount of those calls for this month. Well played vodacom, make it impossible to stop a contract while you debit my account. Maybe it's legal, but it isn't right.