Bad administration from SARS

SARS sent me a letter that i owe them R750 in penalties, they even sent me a statement of account. i made the payment of R750 but now i was told the money was adjusted to R449.57 beacase i had R300.43 due to me. Why was this information not communicated to me, now i must go to the SARS branch to apply for a refund. SARS is quick to send emails and SMSs when they want their money but do not do the same when they suppose to pay you.