The Mobile Service Center Iphone Care - Return of money for service not provided

I had to get my iPhone * plus repaired for the cracked screen and low volume from speakers. When started searching on JUSTDIAL, I received the whatsapp message and call from Zeeshan (+** ***** *****) on ** Feb **** who mentioned that he would be able to fix the issues at my door step and it'd cost me delivery charges of ***/- to ***/- additional to the cost of items to be replaced. I also told him that I'd need proper bill of these parts so as to claim warranty in future if an issue is found for them. I agreed to the quote which he gave to me as: LCD - ****/-, Speaker - ***/-, Delivery Charges - ***/-, Tamper glass - ***/-, GST@**% - ****. He later Added a camera Strip as well to the list of parts to be changed for which he charged ****/-. The delivery charges were agreed to be paid because at the time of finalizing him, I had clearly mentioned that I want the phone to be fixed at my place of stay (door-step service). He. however, took my phone out in the pretext of a stuck screw and then when the speaker's issue was not resolved. I am not sure if he had not replaced any original parts of my iPhone in these * trips. At the end of the day, I was delivered the repaired handset with total bill amount of approximately **,***/-. On further negotiation, we agreed on Rs. **,***/-. When I asked for the bill mentioning all the charges, Zeeshan mentioned that he doesn't have the bill copy and he would be able to provide the scanned hard copy and soft copy next day i.e. ** Feb ****. On his verbal commitment, I paid him the full amount via googlepay at the number (Ibnan Qumani: +** ***** *****) which he provided. The amount included the GST as well. I kept following up for * days starting ** Feb on the bill and was provided the bill only on ** Feb **** after calling Zeeshan minimum a dozen times each on **th and **th. When I received the soft copy, I didn't see mention of GST there. When enquired, Zeeshan told that he will return the amount quoted in the name of GST since he won't be providing GST on the bill. On enquiring when will he return the balance amount, he gave ** Feb * PM as teh timeline. I didn't get money credited till ** Feb end of day. Again a series of calls over phone and whatapp and it's only on ** Feb evening that I was given new time of ** Feb *:** PM. Even that didn't happen. Zeeshan stooped receiving me calls when I started to reach him after *:** PM. He's been non-responsive since then and I am still waiting for the balance amount of Rs ****/- to be credited. It's not just about the amount. It'd about the mental agony and harassment coming from his unprofessional behavior which I am more annoyed over. I seek your support in getting my balance amount back ASAP and due action on this repair center + people running it to torture customers like me. I am attaching the whatsApp chat for the communication as supporting document.