Here is sample letter inquiring the customers about their delay in repaying their overdue amount.
City, State, Zip
Dear ____ (name):
We care about our customers, and we are always searching for new ways to improve our services. For these reasons, we are inquiring whether there is a reason for your delay in paying your long-overdue account. If we can help - by making your payments smaller, by extending our terms, or by recommending a loan company - then please let us know. We would appreciate a word from you - as well as your check.