STANDARD BANK CHARGE RD FEES WHEN FUNDS AVAILABLE

My Cell c debit order of R1277.47 went off morning of 27/01/15. Yesterday morning when I realized I dont have sufficient funds in account I transfered R2600.00 which reflected immediate in my cheque account on 27/01/2015. This morning (28/01/15) Standard Bank send me an sms where they RD my Cell c pmt and penalized me R115.00 for this transaction and additional R115.00 for a R500.00 which were transferred to my Puresave account. THE QUESTION IS, WHY DO STANDARD BANK PENALIZE ME WITH RD FEES WHEN R2600.00 WERE REFLECTING IN MY CHEQ ON 27/01/15??? PLEASE SOMEONE ASSIST ME AS I FEEL THIS IS UNFAIR!!!!