I would also like to summarize few patterns with non-paying clients:
- Once they decided not to pay, for whatever reason, the response is always that they are not happy with the quality of work. Fortunately this is not something that can be used against developer especially if he/she has e-mail confirming intent to move forward.
- They will try to delay the payment asking to split it up or to pay later. NEVER agree to that as this is only trying to delay things. Set the date for payment and if this date is not met consult lawyer or collecting agency.
- They will find excuses and I am not surprised by the comment "I did not contact you due to sensitive nature of what he needs to say. I had very similar response. Again, this is only excuse allowing them to postpone things.
- They will fed you breadcrumbs: small payment, delaying payment, telling you that they don't have time but in a month or so they will so something about it. The only purpose of that is to delay things because non paying customer counts on that you will get tired about getting your money, move to another project and forget and finally things will be forgotten.
Never fall for any of the above. If you know you have done good job, don't be afraid to do anything to get paid for it - you deserve it.