POOR CUSTOMER SERVICE

I have called in your offices today at 15:50 to get a update on my query regarding the double payment and what the process is. The person I spoke to for once has no customer service skills (speaking over a customer while I'm talking not even trying to hear what I'm saying) She went on saying that she received nothing from me without even taking down my details to check my account. I then told her everything was sent and she said she would check it for me, I was 10 minutes on hold when she came back to me and said that I requested to change the payment date and that I could not be refunded which I know can't be the case. I specifically said I can't afford to make two payments so close to one another so the one payment has to be reversed for the 1st of August, she then went to go to a supervisor who I spoke to who seemed nice at first but then also placed me on hold for 2 minutes, he then asked me what is my understanding. While I was explaining everything again to him the line disconnected on me, I believe that I was cut off because he didn't try and call me back. I work in a customer service call centre and dealing with a customer they way they have today is just appalling. At this moment I feel like I want to cancel using my services with you due to the way I was treated today. I want to know your complaints handling procedure because this is not acceptable for you to treat a loyal customer that pays on time every month this way is really not good service.