I work on a freelance basis for an organisation. Most of my payment comes from clients found for me by the organisation, but some of my work is for the organisation itself and in this case they pay me directly. The organisation then takes a percentage cut from the work I do for clients which is billed in arrears.
When they invoice me for their cut they expect payment within a fortnight, yet on most occasions it takes them a month or several months to pay me. Needless to say I'm getting a bit pissed off with this double standard.
Am I within my rights to delay payment to them or could I get myself into hot water? Should I make it explicit why I'm delaying payment and, if so, how should I word this so as not to sound petulant?
Thank you.