Poor rental administration - Day light *******

I gave my notice to the rental administrators responsible of Thatch hill estate for the change of debit order date in October 2017, and I requested it to be effective from November 2017. November went by and debit order was not changed and now its December and they expect me to pay arrears for the December rental just because someone didn't do the change on their side. They debited my account today and i reversed it after talking to them. All i am getting is our apologies yet am expected to pay for interest because my account will now be in arrears. I do not see anything write with this at all levels, this is **************** and someone at central development should account and load the debit order as requested in October 2017.