You get a phone call from a debt collector and they get abusive. What do you do?
Simple: hang up on them. Don't take their crap. THEN . . . get a recording device (like an answering machine with a recording feature) and the next time they call, advise them that you are recording it. If they start swearing or making false accusations, keep it and advise the FTC.
Get familiar with the FTC's Fair Debt Collection Practices Act. Here is a link to their PDF publication.
A debt collector's job is to get money from you. They will also try to guilt you into giving them your bank account number or credit card number. Don't do this, under any circumstances.
**Please keep in mind, the advice given above is only my opinion, and your situation may be different so it would be adviseable to seek legal counsel**