refund shortfall

I refer to my case number *** where I paid you R15000 in error dd Mon 28 Dec 2015.I received a refund in my account to the value of R14495.I am hereby still unhappy since there's a shortfall of R505 which coincidently is exactly my monthly subscription amount.I'm guessing that the person who refunded me assumed that I meant to pay my subscription when paying the R15k in error.My monthly subscription is due on the 27th of each month & if u bothered to check your records u would have noticed that it has already been paid.again I request that the shortfall of R505 be paid into my account asap as I will not rest.thank you.