The first time I went to pick up my bike.... the BRAND NEW chain SNAPED. this took 12k miles to happen on my last chain.. not to mention how badly i treated the the old chain. I WAS FURIOUS!
Likely cause: Improperly installed pin. They did you a favor with the master link. I won't even use the antiquated manually installed pins anymore.
Took it for a test ride: Chain pops off... bring it back... they adjust it... test ride.. again chain pops off... this happened about 5-6 times before it got better.. YET the chain still pops off.
Likely cause: Improperly adjusted low limit screw in FD. Trivial to adjust.
http://www.parktool.com/blog/repair-...ur-adjustments