First and foremost, try going back to Rayford's office during Act III and talk to Jan. If you choose the right dialog options, he may help you out in various ways. Secondly, it's possible to free the prisoners in Rayford's dungeon. I'll leave it to you to figure that out.
Third, you can get help in Tyr itself by rescuing the imprisoned Tyr's Arrows and the city councilors. You just need to go to the parts of the city where they would logically be found, and the rest should take care of itself.