On Air tv **********

OnAir tv is happily taking R119 a month off my account since they delivered the promised new explora in April but as yet I am still waiting for the installer to make an appointment with us. Basically they are *****ing our money without delivering on their promise of free installation and replacement of old dish. I spent about half an hour on the phone with them asking all sorts of questions when they made the offer and some young South African asian voice was very convincing and could answer all my queries but the decoder has been lying here in its packaging since April.how can we stop the debit order?