Hate to tell you but if the same symptoms keep returning, than the originol problem has not been fixed. Your situation is typical with many car makes, a mechanic who is not properly diagnosing the problem. You need to get another person to look over everything, not just fault codes, Many times a fault code is the result of something else, and replacing the first part "in line" is like putting a band aid on a deep cut. If the dealer you go to is the only one available for repairs, I would suggest meeting with the service manager to review the history. Show the manager the records, and how the same problem reappears.

Good Luck
Spence