Money *****ing

Installation and everything went well. I paid for the device and after Installation i get a phone call saying i owe them money i told them i have already paid the amout owed when i purchased the device with the dealership. I emailed them and whatsapp them to tell them i have paid. They then proceeded to take over R1000 out of my account with no warning, after they told me it is sorted and they saw the money. I am going to sort this out with them in the morning but this is not anyway to do business with someone