Web Africa taking money from my account without my permission

I have a faulty router which Web Africa replaced. However they never took the old one and now after months of not collecting the old router they charge my account with R999 WITHOUT MY PERMISSION or informing me that they were taking money from my account! The only way to get hold of them is through whatsapp and that is a STRUGGLE on its own! Can someone from Web Africa contact me so that this can be sorted. You are not allowed to take money from my account with out my permission!!!!