Flipkart — Unable to update mobile number - Arijit Kar

I have created flipkart account 3-4 years back with a mobile number that I no longer have access to. I have access to the registered email but Flipkart is not letting me update my mobile number using email verification.

When i tried to update my new mobile number, the otps are being sent to both the new number and the old number. I got the new number otp and account password, but the otp of the old number cannot be entered as i lost the number and i dont have it. This is making it impossible for me to change the mobile number.
Please help me to update my new mobile number to my flipkart account.