Shocking Customer Service

Once again, Rain has switched off my internet even though each and every month I have told them that I have changed the debit order date from the 25th of the month the the 1st.They have confirmed multiple times this year that the payment date has been updated, however once the 25th hits they keep on trying to bill me. Also I spoke to someone once who was helpful but the error continued shortly after? At this point I am extremely shocked at their service.