Instalment Debit Date

I was out of town and without signal for a month. When i came back , i recieved an sms to request me to confirm my installment debit date. I was supposed to respond on the 4th of December and i called in today on the 7th of December to be told that i did not respond in time therefore i had to bear the consequences of my account bouncing as i am not being paid on the 11th but only on the 23rd of December. The lady i spoke to firmly told me that the account will bounce and i will then be listed on ITC. What happens to my effort for calling and and trying to inform Nedbank of my predicament. No it does not matter, I DID NOT CONFIRM ON THE 4TH AND I AM LATE BY CONFIRMING ON THE 7TH. i am late by only 2 working days!!