Bogey, Do NOT give them your bank account number. No way, no how.

Talk to a lawyer and find out what YOUR rights are. As Klyd pointed out, there's legal aid or someone out there who will provide advice at no charge. Try your local consumer protection agency, anyone that can offer free advice and clarify your rights for you.

These collection agencies are counting on the fact that you don't know what your rights are. They try to intimidate you. Surprise them by speaking knowledgeably about what they can and cannot do.