Horified that a company can deduct money without your permission

Our tracker was installed 4 years ago and has not worked properly for the past year and we have continued to pay. Netstar came to fix the device and we were told that there was no charge. Without a quote, invoice and without our permission they deducted R2200 from my FNB account. I have tried to sort it out with them many phone calls and emails and I am still waiting for a straight answer. Suddenly there is an account and 3 charges ....... Netstar you will loose customers should you not sort your accounts out. I am one of them.