Changing debit dates without consent!!!

I am extremely frustrated with Budget insurance. I indicated that my pay day is the 20th of every month and even my bank debi-check indicates that its the 20th of every month yet they decided to inconvenience me by debiting on the 18th. This is happening for the 2nd time. December debit was on the 17th, no communication, nothing, just inconvenience after another. The money in my account is meant for something else and now its gone. I wouldn't recommend them unless they sort out their ****ty service. Its better to move to another insurance that will understand that I have other responsibilities and commitments