Poor service from Vox, yet again

About a week ago on a Tuesday evening, I lost wifi/internet connection. As it was late, I decided to call the next day. After numerous unsuccessful attempts, I managed to get through on the Wednesday evening. After doing some tests with the operator, it was found that the power supply broke and needs replacing. I informed the operator that I will not be at home during the day, as I needed to be in office on the Thursday and Friday. The operator then assured me that someone will call me the Thursday to confirm a time for the technician to come out. I did not get any calls from Vox on the Thursday and decided to wait until the Friday. On the Friday, I get 3 calls from an unknown number and upon answering, the person told me that he was a technician and was at the gate of my complex. I then asked who he confirmed a time with, as I specifically said that I was not going to be home during the day? He informed me that the office sent him. When I got home the Friday evening, I tried calling Vox and after numerous unsuccessful attempts, I finally managed to speak to someone who then confirmed that a technician will come out and will be there late. He also told me about a call out fee, to which I objected, as the power supply was not my fault. A technician finally arrived around 8pm the evening and replaced the power supply. He left, without mentioning anything about a call out fee that will be charged. On the Tuesday of the following week, I get an email with an account, stating that I owe Vox and that my account is "overdue" with R1436!! I tried calling to verify this and request the recording of the initial phone conversation, but just could not get through. I need to know why I am being charged for a call out fee, as well as "on site labour", if the disconnect was not my fault to begin with.