Telkom incorrect invoicing

I would like to write a review of Telkom, my monthly payments was up to date according to the invoices I received from Telkom up to end of September. When I opened my October invoice the amount was more than two months of normal monthly payments. I phoned in to ask why my October invoice is so high, I got told that I was invoiced wrongly from the month of August and they added all the outstanding amounts to the October invoice and that I must now buy airtime to make a payment arrangement for their fault. This is just very poor service from Telkom. There was no email sent to say that they made a mistake and make arrangements accordingly with me. I will contact Ombudsman to see what we can make of this. Please rectify urgently.