Fair Debt Collection Act

I have been served on an old credit card debt (last payment in February of 2008) and would like to offer a settlement to a 3rd party collector - offering up to $8,000 on $26,000 debt. This collector and several others that were assigned to it before repeatedly violated FDCPA. The suit, in fact, was served at my in-law's home, a place in another parish where we have never lived or listed as our address. We have repeatedly given them our correct mailing and physical address. A collector also called my father's home and told disclosed specific details regarding the debt - amount, creditor, etc. Should I mention these violations in my settlement letter or let it go?

Can bill collectors call on Sunday?

I need your help in getting a 30 day late mark off my credit report. I have a department store credit card, which I pay off every other month. They say that my first payment was due on the 8th of the month and I paid it on the 17th. Then they say that I didn't make a payment at all. I don't know what's going on but I pay all of my bills on time. I don't know if they are not processing the payments until later or if they are arriving late through the mail. I have paid the Target card off regularly and they refuse to take these bad marks off my credit report. My credit report is extremely important to me. What can I do?