Unable to get this card closed

I cannot get Discovery to close this card and charges keep piling up. I was told I could cancel via email, which I did at the beginning of April. I paid the bill, the settlement figure arrived a day after I paid. I sent back a reply with proof of payment and yet still the card is not closed. Two weeks later they sent me a form to complete. Which I did and yet the card is still not closed and still attracting charges. I asked again this week please close the card and received a standard reply of ways I can pay my card :). I no longer live in South Africa and can no longer transfer from one account to another on my FNB online banking. Contrast this with closing my FNB Petrol Card where I followed the same process - sent an email, paid the settlement and the card was closed immediately. Discovery simply refuse to close the card and the bills keep coming.