Capfin bad service

I have a loan agreement with capfin and always received good service from them. On 2 December I received a SMS advising that the debit orders will be lodged earlier than usual due to earlier than usual pay dates. I responded to capfin advising them that my pay date does not change and my debit order to go off on the normal dated which is month end. On 24 December I received my income from an investment I have and has never been a problem for capfin as my debit order is month end. To my surprise a debit was lodged by capfin, which resulted in my account being over drawn. Capfin is now so full of excuses and refer to terms and conditions, however their terms an conditions state contrary to what they did. I specifically responded to their SMS to not change any debit order dates.