Merchants' Credit Guide Co. review: This company has been calling repeatedly, not saying anything, but just calling and hanging up on a continual basis

This company has been calling repeatedly, not saying anything, but just calling and hanging up on a continual basis. You can hear the person breathing on the line. I have asked the person to stop calling and when I do they just hang up. Then a couple of days ago I got a letter from them attempting to collect on a time barred debt. What gets me, is I went through a very traumatic incident and was unable to work. I paid for their unemployment insurance which paid the cc company. The card limit was only 600.00. Now they are asking for $3, 483.46. How can this be. The statute of limitations ran out over 3 years ago. They say they are collecting for PINNACLE CREDIT SERVICES, and the orginal creditor is Providian National Bank. Providian is out of business. They have been out for several years and I know that any money sent in would not go to Providian. What should I do? I read on another site, not to even acknowledge the company because you could mistakenly restart the SOL clock. They have demanded in the letter that I send them my bank account information and they will debit my account for a one time payment of 870.87 or 3 payments of 1741.73 or I can tell them what I can afford to pay each month and they will only debit that amount from my bank account each month until the entire 3, 400+ dollars is paid in full. They also have an office listed in PA now, PO box 1259 Oaks PA 19456 I don't think I owe this money. I paid for the disability insurance on the card and feel that I am being harassed by the breather calls and the letter demanding bank information.