Something about this sounds a little hoaky to me. The post-dated check thing sounds a little weird. How does that "assure" them they'll have payment any more than just writing a check dated today? You could be lying, you could close your account, there might not be money in it, etc. That doesn't "assure" them of anything, so why the insistance on a post-dated check? And in a case like this, it's not a particular good idea to be getting a friend's checking account involved.
Besides, how do you set a payment plan over the phone for a post-dated check? You can agree to a payment plan over the phone. You can set up something to allow them access to deductions from your bank account, but that's a very, very bad idea. You can also wire money. But it doesn't sound like what they mean since that stuff could be done with a savings account. You're talking about writing a check -- you can't write a check over the phone. So the whole doesn't even make any sense.
So why can't you go get a money order and send that? They'd have to wait on a check anyway. So you can still set up the payment plan and then get a money order to send in the payments. What's wrong with that? That is just as good as saying you're writing a post-dated check. What they're saying sounds more like a form of pressure since it doesn't make much sense.
Be careful with collection agencies. While you may have a perfectly legitimate debt that you are responsible for, and therefore should absolutely pay, collection agencies are not always on the up-and-up. They'll outright lie and try to scare the pants off you, to force you into something. And yes, they do illegal things. Sure, you should pay your debts, but everything should be done by a plan and all legal-like.
You didn't give the background of what they are collecting on, so you may already know all this. But do make sure before you send them one penny that you know exactly what this debt is and that you legitimately owe it. Also make sure you have IN WRITING the actual amount of the debt. If you have only spoken with them on the phone and have never gotten something written in the mail with that dollar amount on it, don't pay anything until you do. And I don't mean whoever the debt was originally owed to. It's now in the hands of the collection agency, so have something in writing from them.
And it doesn't hurt to google their name and make sure they don't show up on any of the "shady" lists that are around.
