I'm not mean... really. Yes, I'm a typical controller who has the unpopular task of juggling account payables and account receivables but that's as far as the stereotype goes because I'm really not that mean... as long as you pay your bills on time!
Keep me informed. Actually, while I certainly do expect and appreciate timely payment, if payment is going to be late, all I ask is to be informed accordingly. A simple phone call or email will suffice.