No trust in Nedbank

On 22 September 2015 I make a follow up on an earlier request to correct my account after proof of payment was sent that has not reflected on the account since NO feedback or response was received after the proof was sent to Adian a while ago. On the 23th confirmation was received that the payment was successfully allocated. I sent a follow mail again the same day asking for proof that all is allocated. Again no feedback received. Today I check the account and noticed that an amount for R 1500 made on 23 August 2015 is not allocated. But then Nedbank think it wise to charge me interest for an overdue account that is in fact not overdue for a second month in a row. How long is a reasonable period to get the problem solved? Service is not in their vocabulary yet. Not even an apology for the snail response