Woman wouldn't tell me her employer's name (MCS). I told her I wouldn't confirm any information over the phone, she'd have to mail me a letter requesting my verification. I got her to tell me what address they show, it was wrong. She quickly figured out she couldn't send me a letter and hung up.
I owed my bank roughly $800, they sent it to a debt collector and I made a deal with them to pay $500 to clear the whole debt. However, for whatever reason, THIS debt collector is calling regarding the same debt. I spent an hour on the phone explaining that this debt was resolved, and they promised to investigate and get back. In reality that just means "we'll wait 2 days before we start calling you 3 times a day again". I'm now just disputing the debt on my credit report and waiting to see what happens...