AJ is correct. If you do not pay your bills then ALL of your clients will go down. When your clients do not pay you it can hinder your ability to pay for the services they and others are using.
We deactivate accounts that become too far past due after sending notices alerting them to this fact. A business cannot afford to lower its quality of service for the paying customers because of becoming too lax with the nonpaying customers and trust me..the more lax you become the more non/late payers you will have as time goes on
If they have opened a line of communication with you, then by all means do what you can to work with them but if no communication has been opened to setup an appropriate payment plan then it's time to cut the service. Many people "cancel their accounts" by not paying... they often ignore a host's cancel form leaving you holding the bill for the hosting you provided that they have long forgotten about.
We do, if it comes to the account being deactivated, charge a $10 reactivation fee. We also delete accounts that have been deactivated for over 30 days.