Unauthorised change of payment arrangement

I just received an email that informed me of ammendments made to my payment arrangement. In the email it says that i have agreed to the changes, but no one has made any contact with me what so ever. I have to approved nor agreed to any payment amendments. This new agreement is not acceptable as they have changed my payment date to a day of the month before my salary is paid. this is unacceptable and will be reporting a case of ***** !!