Hi,
You didn't mention who's calling you, I mean the name of the company. If you owe money to some financial company and you've defaulted on them badly, it is quite natural that your accounts will be handed over to the collection agencies. Though the FDCPA protects the rights of the debtors, yet there are some limitations. They can't call you before 9.00 a.m in the morning and after 8.00 p.m at night. They can't call you when you're at your office. If they're taking such actions, then they're violating the FDCPA rules and you can complain against them.
However, a much better option would be repaying your debts. Resort to debt relief options and simplify your debt repayment procedure to become debt free and avoid all the collection calls.