The letter intends to inform your client that you are no more willing to provide any services to him/her since he/she has not been paying bills regularly on time. You mention about the contract that has been signed between you as a reference which reasons out your act of terminating your services towards him/her. You also request the client to pay the outstanding bills. Through this letter communicate those problems and your future decision to work with this company. Here is a good sample regarding the same.
Mr Lakshman Kumar
Yamuna Mineral Water Co
#1213, SP Road
28th January, 2010
M/S Saint Hospital Pvt Ltd
# 2341, Balaji Nagar
Sub: Termination of Supply of Mineral Water.
Ref: Our Service Contract dated 20th October, 2009.
We would like to bring it to your notice that as per our present service contract cited above, our services towards you stands cancelled owing to delayed and irregular payments by your establishment. Our services to you remain terminated with effect from 20th February 2010.
We request you to kindly make the payment for all the outstanding bills by 10th February 2010.