Debit Order Change Date

I have not received any bad service from Getbucks EVER, until now. I have sent multiple requests for my debit date to be updated from the 20th to the 25th as per the change across the company. Only one account was updated as requested. I don't want to be in arrears nor incur unnecessary bank charges in this regard. The first Ref: (29473) for my query on 26/01/15. To date nothing was done. Please update ..