Help! Do I have a leg to stand on here?

I drive a 1998 Toyota Avalon with approximately 201,000 miles. My check engine light
came on last week, so I made an appointment to get it diagnosed and fixed by a
mechanic. I asked him what the codes were, he said there were the following codes:
171, 303, 305, 300. He diagnosed the problem as being the Mass Airflow Sensor and
replaced that. The whole thing, diagnosis, part and repair totaled $275. Now, 3 days
later, the check engine light has come back on. Clearly, this was not the right repair. I
feel like I should not have to pay for any subsequent repairs seeing as he performed a
costly repair on my car and the problem is not fixed. Do I have a leg to stand on here?