Bajaj Electricals — bajaj platini microwave

My mother had bought a bajaj platini microwave on june 2017 through amazon. The serial no of the product is ga[protected]. The model no was 4900050-px-140 mm20c. She was out of town at that time. When she came back she called for demonstration. Bajaj people came and they had told that the product is defective. They will exchange the product. The call no was - kol [protected]-1 dated 12.8.17. They had given a replacement tag and told that j. S. Enterprise will replace the product on 23.8.17. After that we had called daily and several times for exchange the product but everytime their answer was we will do it tomorrow. On the month of november after many phone calls they had sent one person who took away the product against rs 500 and he told that he will bring back the fresh product on the day after tomorrow. Today is 7th march 2018, my mother still has not received her new microwave. Whenever we call j. S. Enterprise, their boss gopal kundu picks up the phone and says we have not received the replaced item yet. My mother is a senior citizen and is being harasshed for her own product day by day by this person. Bajaj is a renowned company, how can they do such unethical things? Please let me know how do my mother will get back her microwave.