2007 "Impala...starts" moving when I shift into 3, only gets to about 27 mph but will not-"shift." Was going to change out shift solenoids but, was told that the 2007 has a computer in the transmission that is specific to VIN and that even if I replaced the solenoids they wouldn't -"work." Also, if I installed a used transmission from a wreck, it wouldn't -work because the computer wouldn't match my vehicle. My only option is to have mine "rebuilt." Please confirm if this is in fact true OR just a mechanic wanting to make money off a rebuild