Denied warranty claim on carbon bike due to impact?
I'd not take this "statement from authority" as an absolute truth.  Ask them to prove its impact damage.

Depending on your location, there may be ombudsman services or small claims courts where you can pursue them for "failure to honour warranty contract"   


If the frame is replaced, they will keep the old one and you look after your new one.
If the claim is rejected, you should contact a carbon fibre specialist and have it checked out.  If a repair seems worth doing and affordable, go ahead.
Otherwise don't be a sucker to buy the "discount" frame.  Consider another brand who does honour their warranty.  It'll happen again.