There are a few things here:
1. Compensation for downgrade.
If you have already flown (accepted the changes), and at least one segment was in int'l F, you are not owed compensation. If the whole trip was downgraded to J, then you can get the difference in miles back.
2. Compensation for lost baggage.
You may get compensation under Montreal Conventionor under DoT rules, depending on the circumstances. Try reading this NYT article -
http://travel.nytimes.com/2013/03/03...pagewanted=all
Also, see if you had insurance on the CC to which you charged the taxes - you may be able to get more that way. Keep in mind that your CC insurance may require subrogation of claim against the carrier - read documents carefully or consult an attorney.
3. General advice.
When you have problems like these, you should request a supervisor. Most agents wouldn't be able to help competently.