Either get your money back, or get some of it back. Replacement value is a concern, since you won't be able to get an identical bike w/out the crack for the same money. There is some value in the low price...

The frame is probably worth $150 used? So look at what that bike should be worth and drop off $150 or $200 (for the build-up labor). Then drill your hole and use the clamp -- should last.