Capital Security's accounting

I've asked Capital Security in Worcester to look at my alarm due to problems I've experienced. They came out fixed the problem. I got an invoice for R291.00 for the call out. On 10/02/2015 I paid them. EFT. I received my monthly bill last month and saw that they say I did not pay them. I called them and Cathy told me that she can see that the money was paid. I asked her to get a message to the account department to call me. Nothing. Today again a bill and now the amount is R434.60 behind. I would like to know what happen to my R291.00 that I paid in February was it ****** by someone at Capital and before I forget I am finish with Capital. AC Security will be my new service provider.