Here's some free advice. A kinswoman made the mistake of making a partial payment via "check by phone" to a collection agency. The agency failed to use the check number she provided and threatened to withdraw more money from her bank account even without her permission. She had to close her account and open a new one.
I've been trying to call to complain on her behalf, but the numbers don't work and the HQ claims its "system is down" every time I call to report a crime in one of their offices. I suspect that GC Services of Houston, the disreputable company in this case promotes threats of theft and downright theft.
The advice? Don't pay anything to a collection cvia "check by phone". You might as well give your account information to a Nigerian e-mail scam artist.