Flipkart — regarding lg g7 thinq exchange imei flipkart not working

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14-136 2nd Floor Bommidi Building Beside Reliance Bunk Road Near Rtc Complex, East Godavari, Andhra Pradesh, 533103

I am not happy with flipkart.
Five months back i brought lg g7think from flipkart.
Now i want buy a new mobile with exchange my lg g7 think mobile. So i decided to exchange . I selected oppo reno to buy. I opted to exchange in flipkart exchange programme. I filled all details like brand, mobile model. But problem starts here when i filled my IMEI number, it say " ENTERED IMEI NUMBER DOES NOT MATCH With SELECTED BRAND AND MODEL" i also checked my FLIPKART INVOICE IMEI. NOT WORKING...
I AM SUBMITTING WITH PROOFS .