On second thought, I bet the 'Mechanic" fouled the connector to the new ABS module. Sadly, the ABS module was never at fault, as your original complaint of "spongy" is not an ABS module issue, it's a mechanical issue with the master cylinder, fluid or wheel cylinder.

Who knows what they did, if the speedo worked at first and died as you drove, maybe the RCM has failed (it happens a LOT) or maybe the connector on the ABS module was not seated properly when they worked on it - easy fix, I would think. BUt make sure you take it back to the same shop, no one can REALLY mess this up like they can.