Having been with a company in the past that did not pay (thankfully not this one), whoever called the most got paid first just to lower the call volume.  Also e-mail and fax at the same time or mix it up.  The only thing is if it is one order and the only order you have gotten or a company that only uses you once in a while; from a business perspective if they are having a monetary crunch you are low on the totem pole for money because they also have large suppliers probably screaming for money too.