They will fix it for free. Just take it back, and tell them they need to set the timing and try to get it to idle at least as good as it did when it came in the first time with a bad distributor.

Sounds to me like they swapped it out for a new unit, and didn't set your base timing. Either that, or they did set the base timing, but your car hadn't warmed all the way up before they set it (it must be at fully warmed operating temp to do this). It should take them less than 5 minutes to fix.

If you paid for the repairs and didn't make an ass of yourself somehow... like paying them in pennies or screaming obscenities at them, then there's no way any reasonable shop would make you pay for their help on something that just left their shop that still has the same problem...

Good luck!