The ammonia is very hard on your fish. 3-4 is still very high. It's unfortunate but without another tank to move them to til your tank finishes its cycle, and since they've been exposed and weakened for so long by the ammonia, I'm not surprised your fish are still declining. I really don't know what to suggest other than to keep doing what your doing with your water. Keep in mind this is just the first hurdle for them. Once the ammonia starts to fall, there will be a spike in nitrites. Your gonna need a nitrite test so you can watch these as well. This is also very harmful to your fish. As for the ammonia in your tap, again, unless your parents are willing to buy some water to dilute your tap, or to buy a filter to filter it out, I don't know what to suggest.