Payment done but they are claiming that i didn't pay

<p>On the 26/07/2016 i received a call from DSTV saying that my account was overdue but i already paid it on the 20/07/2016 and I also have proof that is being paid when i told them that the money went off on my bank account they telling me that the last payment was on the 21/06/2016 ,please double check your system because i made a payment with the right reference no</p>