Samsung service centre - Phone not delivered on time

I had given my Samsung A* phone for repairing of charging jack at Cell Well Samsung Service Station in Karanagar Srinagar on ** Jan ****. They said they will replace the part and will give back my phone after * days. But till date, I have not received their phone call nor they receive my calls. Only one time they receive my phone call in which they said that they have changed the part but the phone is not responding. They received the phone after proper check and in on mode. I also visited there but they said that the employee is not present, please come after some time. How can I visit regularly?
The cost of that part was **** and I had also given *** as advance payment. It costs me too much as my *nd service provider sim was off due to their negligence and I lost the best business offer costing * lacs per month. They are liable to pay back my loss and the new phone.