debit order earlier than agreed

Poor service from absa.I recently signed up for an absa life policy and it was agreed that the first debit order should go through on the 31st May 2016.They even sent me an sms to confirm that they got this right.However,on the 1st of May 2016, a debit order was processed by absa.This is nonsense at its best if you had to ask me.They are not allowed to run a debit before the date I have permitted them to do so.It might be argued that it is not a lot of money but I can`t allow someone to abuse their power.I have been banking with them for 9 years.The issue here is the principle which they got completely wrong.