Cost to remove transmission on 2001 Isuzu Trooper

Went to a shop to get a diagnostic done on transmission. Ck engine and Ck trans light were on but I felt no slipping. When I went back the guy said it would $780. When I ask why, seeing as I was quoted $85, He said they did a full diagnostic. One, no one asked if that's what I wanted, two I didn't ask for a full diagnostic, I asked for the computer analysis.I ask the differ, and he says with full diagnostic they take trans out and take it completely apart and check each part. I have never heard of this! I haven't paid yet but trying to figure out what to do. If this is a real thing, what would it normally cost? He is now saying to fix it I need a "new converter, new pump, new valve, and Few kits." Claims the converted is busted and caused everything else to be damaged.

Asked by for the 2001 Isuzu Trooper
Best call your consumer afairs office in your state. This is common tactic of tearing car down to force you to either pay a high price to repair or as many folks do just abandon the car. If you did not sign anything authorizing them to take transmission apart it seems to be a dishonest repair shop in my mind. Seek legal advise for the laws in your state.
2 more answers
u could be looking at upwards of 3000.00 seek a free diag from aamco.if the shop did the diag the deserve there fee
Did you authorize a $85 diagnosis? or a tear-down estimate of $780? If you can prove you signed a work order for only $85, the law will be on YOUR side...however, IF you signed something saying you want a complete diagnosis with a are out of luck...I sincerely hope you did not sign such paper!