Xiaomi India - poor service and improper conduct and fraud

let me give a detail of the series of incidents.
*. i had a display replacement with job sheet id: wxinWXIN************* for which i paid **** but when i returned home i found that the fingerprint sensor and camera were not working.
*. for the above service issues i raised a complain with id: woin************* and i was asked another service center for a check-up.
*. on *-**-**** i visited the other service center where they told me that the motherboard has been liquid damaged during screen replacement and this will cost me ****/- for which a job sheet was opened wxin*************(open job sheet id) on the request of mi cc executive.

noww as per the latest call that i received from one of the mi executives rohan(phn no. **********) a complete replacement will be done for the phone along with the reimbursement of the screen change charges.
but the worst part is that i have not received any communication in written for the same plus he is asking me to pay ***/- as the delivery charge through paytm.
the amount is not the issue but until and unless i have a written confirmation it makes no sense to ask for the payment.
request you to look into the issue and provide a resolution at the earliest or if replacement is too much of an issue i request you to refund my complete money ****+****=*****/-