I used to have the same problems when I was a theatrical agent, client fees were always late and the bigger the production company or ad agency, the later the fees. I had a number of tactics that worked with various degrees of success, and include:
1. An invoice with was higher than the original quopte, with a note stating that payment within X days/weeks would be subject to a 10% settlement discount (that would reduce the amount owed to the quoted price.
2. As above but would state to the company at the time of quote that the above would apply.
3. Offer a 10% discount on the next job if this invoice is settled on time.
4. If the payment is a day late call them and ask if they are in fananical difficulties - only you heard from an associate that he hadnt been paid either/the company was in difficulty (that gets staff worried too!).
5. if what you are producing is broadcast, then threaten you'll have the TV company withdraw it, as the copyright for them to broadcast is granted only upon payment - I've actually seen that on contracts for commercials, music videos and even corporate videos that are to be shown publicly
6.Send a letter saying the late payment is being escalated and referred to a collection agency and advise that if the debt is handed over to a collection agency, then costs will be added to the original invoice - that's a final one for the real pain in the butt companies.
The problem with our industry is that everything and everyone are so very informal and people do try it on. What is worse is the fact that they can easily take offence and not deal with you again, they also know that you are one of a hundred other video production companies in the area, so tact and humour has often been key to my success.
I once made a headed paper from the ficticous 'Ackney Acme Collection Agency' with 'That' photo of Reggie & Ronnie Kray in the top corner, on the page I wrote words to the effect that if the bill isn't paid by return our 'celebrity duo' would be round to collect payment or bruises to the value of £X - that really did work on more then one occassion - yes, sure you have to be careful who you send that kind of humour to and I probably broke a few copyright laws too but the end result was positive
