hi there,
are you late payers, one off cleans, or are they regular daily or weekly office cleans.
if they are the latter, then you would look to put a clause in your terms and conditions staing that serivce will be withdrawn if payment is not made by a certain date after the invoice is issued.
therefore you then have the right to withdraw the service, and on top of that continue to bill the client. i have seen this doen before and in court the client had to pay all the monies including the invoicing during the cleaning suspension.
the other thing is that if clients dont pay and you stop cleaning, you will usualyy find that they will then pay quite quickly usually about three days with out cleaning does the trick.
dont know if this helps
regards
martin