Dishonesty

I phoned the company on the 25th November that they should remove the device from old car to a new car that I was taking delivery on the 26 Nov. They told me I need a new device and they cancelled the old one, however they deducted on the 1st for the old car, the new car device was installed on the 9th Dec, They now deducted pro rata for the new car for Dec when they had already took money for the old car. I contact them after seeing the invoices but they still deducted both invoices