Martha realizes that the microwave she bought is faulty after a month of purchase. The manufacturer of the microwave asks Martha to pay the repair expenses as the fault was with a part that was out of

Martha realizes that the microwave she bought is faulty after a month of purchase. The manufacturer of the microwave asks Martha to pay the repair expenses as the fault was with a part that was out of warranty. Martha was unaware of this warranty condition. What should Martha do to resolve her grievance?