I have a three month old Madone 6.2 with Di2. I love it but not the bike shop. Having serious problems with their mechanics and now wondering if my bike could be compromised.

I've had rattling in my headset area, problems with installation of rim tape which caused flats (at 35MPH downhill) and recently the crank arm on my left pedal came off (they said a cotter pin wasn't installed - I later found out that cotter pins haven't been used in several decades.) Every time I take it in, I ask them to go over it & they say they did. What I get is a bike with new scratches & eventual problems. I'm having concerns about their initial assembly - especially if they tightened the frame bolts with the correct pressure. I wrote to Trek & they said the warranty dept. would be getting back to me, but nothing yet (it's only been a few days.)

So, here are my questions:

1. How much of the assembly is actually done in the bike shop? If the factory torqued the bolts down & did the major assembly, I would feel better. This is a Concept One store, so supposedly the mechanics have been trained but I really doubt it.

2. At three months old, if the bolts were torqued too tightly, would that have compromised the carbon fiber?

I'm really disappointed, having shelled out big bucks for a bike that I don't feel confident in riding over 30MPH.

Thanks for any & all advice!