Unauthorized debit order change

You changed my December debit order date without my consent. The only notice you gave me about this, was an unreliable sms, which I'm very lucky for getting, which stated that my debit was changed. If I had not taken my employers time and called in to changed it back, you would be taking the money kept for my children when I would be unable to replace it before the holiday closures. When I started the loan, the December debit was mentioned. I stated then very clearly that my employer sticks to the contracted pay day and I DO NOT get an early paycheck ever. Why not like other places, ask me to approve an earlier debit order instead of you doing what you want. I have a long standing relationship with you, and you betray me like this. Shame on you.