Yeah your 95 should just be like my 93 and all i did was take out all screws and the stock head unit pretty much just fell out lol.
I didn't even like take the dash apart just the whole center area and it was a snap. I have a feeling like the guy above that when the old owner added that radio he added something to make taking the radio out hard, thus the problem you are having.
I feel your pain about the installer as i did my whole music setup myself and did not pay but you might be in a situation where you may need to pay to have someone really get in there.
I have not had this car for a long time and have not ripped the dash apart to really give any other guidance other than i think you did do it right and i have a feeling that someone added something and that is what is making your life difficult.
Wish i could be better help