You are working with what are two different SOL time frames (statute of limitations). One is for resetting the SOL to legitimately sue (which can happen), and the other for re-aging the time for a negative item to remain on your credit report (which cannot).
One set of laws will vary by state, and the other is covered by federal Fair Credit Reporting (FCRA) laws. Lets take a look at how both apply to you given the information you shared.
SOL to legitimately sue in your state.
Michigan, similar to many other states, has a 6 year limit for how long you can be sued for collection on open accounts, like revolving consumer credit cards; loans that may be revolving, like personal lines of credit; and even loans that are fixed, and governed narrowly by a written agreement.
If it has been six years since you last paid anything on the debts at issue, Milan Investments, nor Oxford Law LLC in Pennsylvania, can legitimately sue you. That is to say, they could file the suit, but you can defend that quickly and simply as being time barred. The last payment reference of 2011 on your credit reports appears to be erroneous.
In Michigan, you renew the SOL to be sued, when you do so in writing. You can review the governing statute . Speaking to the creditor, a debt collector, or a new debt owner does not reset the SOL clock to sue in your state (but it can in others).
Credit reporting SOL for accounts in collection.
Your credit reports will continue to show unpaid debts on your credit reports for up to 7.5 years from when you first missed your payments. That SOL for reporting is governed by the FCRA at the federal level. There are some exceptions to this, like New York law for paid collections. But I am not aware of anything different regarding credit reporting in Michigan.
With your last payment to the creditor being March of 2007, this should be coming off of your credit report in a matter of weeks. The charge off reporting showing for the following year should not impact this (but unfortunately can). And though you mention that neither Oxford Law or Milan Investments are showing on your credit reports, any collection entry on your credit reports (other than a judgment for the same debt) should fall off at the same time as the loan originators reporting (also something to be watchful of).
You can dispute the credit reporting as too old to continue to appear on your credit reports. Send your dispute to the credit bureaus certified mail return receipt requested. You can send a copy of your dispute addressed to the company(s) reporting the collection account. Keep a copy of all that you send, and the green return cards you get, for your records. Post a follow up to the results of those disputes, and if items continue to show in your reports that should not, let’s take it from there.