I had a metal breast plate (sheild)under my camaro

i had a metal breast plate (sheild)under my camaro before i took it to the shop to have a new fuel pump put on it and it was there to protect it from rainy wet roads and high water areas, i got it in january and it was there when i got it. now my electrical parts in my dash are wigging out because of the rainy roads and i asked the auto shop why they didnt put it back on and they **** there never was one. now i need a diagram of the car so they will fix it and i dont have to sue. keep in mind i just paid $1,200 for the work done on it at the auto shop.