Wrong debt orde dates refuse to change dates but there own policy stayes clearly the must change it

I got vehicle finance via Planet42. My pay slip pay date clearly states pay date is 25th. The deducted on the 22nd. I called then many times and emailled them many times since last year October. They told me on my bank details i sometimes get paid earlier. Thats because of pay date falls on a weekend sometimes. But there brains cant except that. Today itold them again that my pay date is the 25th.. they said tgey cant change it wich is a lie..as there policy document that they give me clearly show that should a paydate or debt order date change i have to tell them 2 days in advance..i did sent them a copy of that .there policy and still to ********. This planet42 admin people are clearly in incompotent to perforn there duties.