numerous phone calls when ive already spoken to them

ive been receiving phone calls for about a month now about ever two hours or so i spoke to them about the bill they received they wanted me to do ach withdrawals from our acccount to make the payment i said no i told them i wanted a copy of the bill from the original creditor which i received and i proceded to tell them i would send  a money order but they still insisted they wanted an ach witdrawal we pay all our bills with money orders they were not threatening but on the verge of harrsment which i think the phone calls are i will not pick up after speaking to them once they said until they receive aa money order for the payment i will still be getting calls even though i told them no calls please help i am not afraid to deal with them these people need to be shut down and the dialer system needs to be outlawed