The salt and heat method may be another alternative for you if you're looking for a more natural approach. You can read about it and other ick remedys in the ick article, linked below.
Fitting in as many partial water changes and gravel siphonings as possible will help in battling ick since you'll be removing parasites with the water. It's not a cure but it will definitely help and if your fish are really struggling right now it might be just the thing to get them past this critical time.
Increasing water movement will also help in the battle.
One word of caution on the heat and salt method: you mentioned a fungus infection. It's easy to mistake a bacterial infection for fungus and some bacteria will multiply in warmer water so if there's any doubt that it is in fact fungal you might want to go with just salt.
I don't know anything about the product you are currently using however given the life cycle of the ick parasite its not surprising that it hasn't worked. Unless the directions warn otherwise you want to maintain most ick treatments for at least ten days.
Don't give up on that tank! Ick is a pain but its definitely beatable so hang in there! Please post back with any additional questions or concerns.
Robin
