It's good that you are seeking professional help with this issue. My experiences as a Property Manager and investor in the city of Detroit have allowed me to observe others make big mistakes seeking quick fixes from shady sources. It is always prudent to go about things the right way the first time.
Try Harold Hoyt of Professional Property Tax Appeals 586-552-8990. I've found him to be competent and very experienced in these matters.
Good luck, I hope this helps.
All the best,
Discount Detroit/Reliant Property Management