We would fix your car for around fifteen hundred dollars. I can say that almost universally because we do two or three a month and when we don't have enough pieces to fix one (a melt down) we will insert a used one. You should be able to find someone in your area close to that price.
The problem you have is undoubtably the lack of application of the B2 band. Unfortunately on 722.4 trannies this usually means a broken band itself. It is possible that the servo piston seal is broken and all of this can be determined without removing the trans. If it is a broken band it will have to be disassembled.
Bosch Master, ASE Master, L1
33 years MB technician