Consumer Redressal

Unique Piped Gas is supplying gas to my flat. In the month of April I have recieved a Bill for 1502.52Bill No 113260 , Bill Date: 29-03-14 Bill Amount : 1502.52I have paid an amont of 2000 and before due date and this was not reflected in the Next billIn may I recieved 1956.34 (which includes all the interest + lat payment fee etc)bill No: 117757 Bill Date : 30-04-14 - Bill Amount: 1956.34 Finally they have adjusted 2000 against month of mayBut again I have recieved another bill , bill no 123656 Bill Date:: 26-05-14 Bill Amount : 280.20 where I argued that, I have to pay very less because they did the credit amount very late, which included all interest + late fees etc. This was not consideredin June, another bill which included all dues (which were never there) bill no: 130663, Bill Date: 25-06-14, Bill amount: 544.47 So I made all the calculations I only paid less amount.So they are never realizing their mistake, continue to do incorrect billing