Tough call here Charles. Everyone runs their business differently while trying to keep everyone happy. One thing you can't ever do, is set fee's where people pay over time. However, you can always have it to where they pay you for what you do that day...and that's what you SHOULD do. Some rules of thumb I use.
1. Communicate with all clients both by phone, email, and of course in person. Get a feel for them before you do business. Schedule a meeting between them and you before any work is done. Call it a client interview, meeting, plan of action or whatever else. You should know in 10-15 minutes whether they will be good to work with or not.
I've stopped so many jobs from taking place this way. I've stopped even more through email. When someone keeps asking "can you do it cheaper" questions or seems to be acting like a tight @ss when I go out of my way to give them better service than anyone alive, they insult my intelligence. No one will get the service I give them for the prices I charge. My time and experience are worth something.
As soon as they upset me and make me think twice, it's over. I came into this world without them, I'll leave that way. I love my job, I love servicing my clients and live this stuff 24/7. When it looks as though I will not enjoy the experience due ot a tude or someone coming into MY world being too forceful or not as "human" as I'd like, I walk. I got people banging down my door to work with me, I will not settle for less. If the Lord takes those that are banging down my door away, I still will not settle for less. I'll get a new job before I'll eat someone's slop for the sake of making money.
2. I work, they pay. If we agreed that they pay in increments, this means each time I work, they pay. Each time we get together, I work, they pay.
3. No one gets any CDR's or rough mix files until they pay for what was done that day.
4. If I do the work and you don't like my work, I still did the work. I could have done someone else's project. I will try to accommodate, but if they are still unhappy and don't want to work with me, they still owe me for the time I put in. This is non-negotiable and there will not be a refund EVER. The client knew this going into it. I have a 3 strike rule. I work on something, they don't like it, I fix it again to their specs. If they still don't like it, it's a set fee per hour.
5. Huge jobs/net jobs: Half down on the entire job. They trust me giving me the first half, once I finish the job....I trust them for the second half. Once I'm done, the rest of the money is due.
6. Releasing the audio so they can take it somewhere else: This is totally your call. They own the songs, you own the media as well as the production unless they pay for it. If you wish to release them, they supply the hard disc/flash drive. If it's a matter of pasting the files onto a drive where it takes 10-15 minutes...go for it and don't charge them a dime. Get them out of your place. Just don't give the tunes away unless you feel you were compensated enough for the creation of them.
Any paste's lasting 30 minutes or longer, require a fee. In 30 minutes time, you can pre-master a song for an album. In an hour, you can literally pre-master and master a complete song for the most part. Time is money. Be as nice as you can, but remember, the nicer you are, the more people seem to take advantage of your good nature. I'm fair but I'm firm.
Anyway, hope some of this helps and you resolve the issue. If not, just get them out of there so they don't cause you any more grief. However, if by chance any of their gripes are legit with you...and you re-evaluate all that's transpired and find maybe you are sort of at fault for some of this (not saying you are, I'm just making you think a little) then by all means try to strike up a meeting and see if there is a way to make everyone happy. Communication is the key...and it's usually best to communicate with everyone instead of hearing from one band member or hearing something said that came from another band member. You'll be surprised at how face to face communication changes things up. Good luck Charles!
-Danny