cannot manage accounts and payments

so I paid my account on the 27th of July with the same reference number I always use as you are created as a beneficiary on my bank. never had a problem with my account but this month my payment was not allocated to my account. kept on getting SMS's saying I must pay. So when I phoned in I was asked for a proof of payment which I sent on the 8th of Aug. When I called again on Saturday I was told sorry we did not receive it. sent it again. today I get an email saying I better pay. WHAT ARE YOU PEOPLE DOING. DO YOU NOT CHECK YOU BANK STATEMENT THEN YOU HAVE THE AUDATICTY TO TELL ME TO PAY AGAIN. GET YOU ACCOUNTS IN ORDER BEFORE SENDING ME ANY MORE LETTERS MR LANCE FLORENCE. I WANT THIS SORTED OUT AND SENT AN APOLOGY LETTER