HELP: Exhaust

I just put the SLP catted X on my car today and it leaks sooooooooo bad... the leak is louder than the exhaust... my mechanic rechecked it and he has the clamps as tight as they go but it leaks at the cats really bad... the slp x pipe is in a bunch of pieces and the cats get clamped in.. i dont know what to do but my car really sounds like crap at the moment.. and on top of that my mufflers bang against something now.. AND the X sits about 2.5 inches from the ground and i already scraped it once on the way home....what should i do? i dont think companies take exhaust back please help cuz if i have to put the stock one back on that would be a waste of $400

yeah i think im gona try some high temp silicone or something this weekend when i have a chance to work on it.. my mechanic really wasnt any help he was pretty much like theres nothing he can do about it... so i guess im left to mess with it... i just hope i can get everything working because my car sounds terrible and i dont want to put the stock one back on... how far will the x pipe go up if i jack it up and then tighten it?

idk what im gona do.. i think im going to try and weld the cats in this weekend.. hopefully that works or im out $400