Aftermarket installation problem

I have a 2003 Nissan Sentra. I bought an aftermarket kit for a single DIN radio from Circuit City. I installed a Panasonic CQ-C8400U and it worked OK until the internal amp died. However, the opening was too tight and I couldn't get the faceplate to open very well. Bought a JVC KD-AVX1 and the chassis is much bigger than the Panasonic. Bought another stereo kit from Crutchfield and the opening is a touch bigger. Now, the opening is too small by about 1/4" on both sides and about 1/8" on the bottom only, due to the placement of the unit in relation to the kit opening. Spent an hour and 15 minutes on the phone with Crutchfield Technical Service and they have no answers. This has not come up before. They swear it should fit but after waiting on hold for more than 20 minutes total time, they did measure the kit opening on their end to confirm what I told them. I know that all I have to do is cut the plastic, which I have done with the first kit, but not the second kit. I want it to look professional and clean, which it does not look right now because I used a dremel to cut the first kit. Any suggestions? Oh, and the trim plate was removed when I measured and the metal sleeve is not being used. I have mounted the radio directly to the factory bracket. The aftermarket kit doesn't not have the strength to use the sleeve because it is merely cosmetic. Thanks.

Ha, I know you're trying to do this yourself and this advice probably won't help much, but I would just take it to Best Buy or something and have it installed. Pull out your deck and your kit and just show up with the deck saying you need it installed.

it'll be like 50 bucks.... added $19 sayin custom, if u bought everything else already, then it'll be about that, and dont let them install it w/o the brackets...