P0778, p0750, p0743, p0962. plz i need help on what to actually do

Question

my car is having trouble moving forward,it makes a misfiring sound and cant produce enough power to even climb a stone.these trouble codes were read by the diagnostics device ; pressure control solenoid B (P0778), shift solenoid A (p0750), torque converter clutch (p0743) and as result i was asked to change the SOLENOID VALVE BODY (TRANSAXLE CONTROL),which i did and the car performed for a day.by the next day i had the same problems and now it cant even reverse when engaged in R. i used the diagnostics device again and two of the previous trouble codes repeated [torque converter clutch (p0743) & shift solenoid A (p0750)] and a new one pressure control solenoid low (p0962) were read. am now being asked to change the whole transmission unit(gear box), please i need help on what action to take.