Hmmmm. Let me get this straight. This is a new bike, still under warranty?
If so, I'd remind them that you didn't get injured from the failure of their product, and how they are completely responsible for the lack of quality control. Then tell them exactly what you expect them to do to correct it. Namely, have a local, certified repair shop come get the bike, and do the necessary repairs, as well as check everything for collateral damage.
Additionally, you could back down a touch and relent to delivering the bike to a repair shop of their choosing.
Force the issue of having them accept the responsibility, as well as all the handling of the matter, 'cause sure as I breath, if they send you the parts, and you do the work, they'll consider the warranty void, due to you doing the work as a non-certified repairman.
Roger