How to use carrier-phase postprocessing in GPS

I want to survey a very few points using GPS and postprocessing with the pseudoranges and/or the carrier phases, and I even have a GPS receiver (the Garmin GPS 17) that outputs them.

But where is all the postprocessing software?

There is Gringo - maybe I will go that way - though their emphasis seems to be getting carrier phase and pseudorange data out of consumer receivers that are not supposed to be able to output them. I did get their demos to fool with.

But I don’t find any others. Rhino Rover from USPositioning seems to be dead - they don’t answer phones or email, and somebody at Garmin told me they thought they were out of business.

My Garmin contact suggested a web site with a mathematical discussion of how to do it yourself, and I may also do this. But it would surprise me if there were no commercial solutions to this, as I thought it was a pretty common thing. Do I really have to figure it out from scratch?