Take the car to a transmission shop that only deals with transmissions.
A general service shop likely either doesn’t want to deal with a transmission repair, and/or they’re just going to send the car/transmission to a local specialist. It could also be a simple problem (solenoid, linkage, etc.) and much cheaper; a transmission shop would be able to tell.
If memory serves, don’t some Ford Focuses of this vintage have a history of transmission problems? Not that that helps here… but if so, there may be a TSB or even recall available.