Trying to cancel a new line for the last 3/4 weeks

I have for last 3/4 week's been trying to cancel this new line. it was in the cooling off period and every time I have phoned, they tell me they will send an email. I phone and phone and I get the same response, I have also been transferred so many times and now one can help me. I am furious and will now take it to your CEO. R300 will go off my account today and it will bounce, and I will need to pay debit order bouncing fees because of this. every cent counts these days.