I am not a fan of nylon bolts and would give HH a call. Β*They have been nothing but a pleasure to deal with for me.
Did you guys know that a single 1/4-20 nylon bolt from the LHS has approximately 130+ lb axial break strength? The axial yield strength (the amount of pull before the bolt starts to give and stretch) is around 90 lbs. The yield strength in the radial direction (twisting) is approximately 30 lbs on the threads. Many years ago now, back when we used to use 3-4 bolts to hold 60 sized wings on so that they could break away in a crash, I performed the testing myself out of curiosity, and was surprised by the results.
Even two bolts holding such a wing would cause major wing damage in a mishap. A single nylon 1/4-20 is good for many applications in modeling
I too have had great dealings with Horizon Hobby Support/Sevice. To the OP, definitely give them a call and explain what happened....