Contested quiet title

[D Weebs]

I recently purchased a home in FL at a tax auction. I am going through the quiet title process and the previous owners are fighting the quiet title after accepting the money. They say they didnt receive notice of the sale, even though they admitted to knowing they had delinquent taxes, and showed up within hours to change their address with the county as to where they could send the check. Also,their iaddress on file with the county is still their home and was until after the tax deed sale where all the mail for all interested parties went. Even though mail came back unclaimed, I'm wondering if anyone has been a part of a tax deed quiet title that was overturned in a similar situation. - d