Upgrade Harassment

I have two contracts with Cell C. When each of them expired (one of them a year ago, the other about 18 months ago), I chose not to upgrade, but rather switch to ChatMore Standard (month-to-month). Since then I've been getting an average of at least one phone call a month, asking me if I want to upgrade. Every time I explain that I've already changed my packages and that I'm happy with what I have. Apart from the fact that they keep phoning back instead of realizing I don't want to upgrade, I've usually been treated with friendliness and respect. Until today. The representative refused to stop, hardly letting me finish my sentences. He kept insisting that my ChatMore standard packages would soon expire (which is not what the definition of \month-to-month"is)"