Residential Warranty Services Inc. Failure to pay contractors Carmel Indiana

We have performed home warranty work for RWS for many years and have off and on always had an issue with getting payment.  We submit our invoices in a timely fashion and per their contractor contract they will pay those invoices in 60 days. At times it has been 6 months without a payment, but since March the lack of payment is pretty much non-existant.  Every time we call we are given the run around.  We have been told checks were issued and mailed and must have gotten lost in the mail, that a check will be issued on Friday, or the person who writes the checks isn't in (that same person never takes phone calls and doesn't respond to emails if she is in).  When asked to speak with a supervisor or manager none are ever available and when voicemails are left no resposne.  I am not sure what has changed so dramatically since March (prior to that we received payment on a pretty regular basis) but the amount of money that is owed to us and several other contractors makes us wonder about the financial stability of this company!!