Double billed

I pay R399 via a debit order for my Dstv compact every month on the 1st. For the month of March, my debit did not go through because of insufficient funds. On the 4th of March when I checked my balance on the DSTV app I was double charged. I went to the DSTV service centre in Lebowakgomo to enquire.I was not given a clear answer why I was double charged. I then paid R399 plus R40 interest. To my suprise, on the 5th of March I received an sms saying I still owe R399. For what? I tried calling their contact center, nobody is available, their service center is of no use cause nobody is giving me answers and their Whatsapp number doesn't answer questions. I'm frustrated but such things because I paid but now DSTV is threatening to disconnect my services. DSTV, you enrouraged your customers to pay for services via debit order. I did exactly that, what did I gain?