+1 on TTM. You name the medication, I've tried all of them and not luck... Copper needs monitoring of copper levels which can be tricky.
Rough summary of the method:
Get yourself two 10 gallon tanks. Every 3 days (for 2 weeks, never exceed 72 hours for each transfer), do a 10 gallon water change for your display tank (if you have not introduced ich in your display tank). Use the 10 gallons from the display tank for each time you do the transfer which makes it easier cause you don't have to check water parameters if you already checking your display tank and you know the water is good. Approximately 5-6 tank transfers, you should monitor the fish for another 2-3 weeks just to make sure there are no more ich. Important you clean and air dry your two 10 gallon tanks thoroughly between transfers.
Goodluck!