Mechanic wrapped a piece of cloth around muffler to fix it, now he won't answer?

My brother bought an infiniti the other day and paid $245 to have the muffler fixed. He took it to a Mexican shop and mechanic had the car for a few days and my brother (who doesn't know a thing about cars) picked it up and took it home however, the car is still having the same problem and upon second inspection by my boyfriend, all the mechanic seems to have done is wrap a piece of cloth around the broken muffler and secured a ring to keep the cloth in place. Now the mechanic is not answering his phone. What to do next? or is there nothing we can do now?