Mi India — not repairing and returning my mi phone

Address:

Gautam Buddh Nagar, Uttar Pradesh, 201301

My phone had some problem and i gave it to service center in noida (Mi service center near fortis hospital, bharat complex). I submitted to them on[protected]. Initially they said they would return it after two days but they did not. Then they said the will return another after 2 days. Maximum time is 10 days after submission. But they are still not giving it back. Everytime i go there they say when the part will come they will return me. I have been there now 6 times. They have crossed there maximum days dedline still they are giving any fix data that when they would return me repaired. Please help me getting my phone repaired. I am facing huge problem without my phone