There are multiple options to  change/ update your mobile number/ email-id in Kotak FASTag records :     1) To update Mobile No. / Email Id instantly, log in with your registered mobile number on https://kotakfastag.in/  >> Click On 'My Profile' tab wherein an 'Edit' icon will be displayed near mobile number and email id. To update your mobile number :     Click on edit icon displayed near Mobile Number Enter your new mobile number and verify via OTP. Kindly note, a combination of OTP will be sent to your old and new mobile number After OTP verification, the new mobile number will be updated instantly in Kotak FASTag profile To update your email Id: Click on edit icon displayed near email-id. Enter your new email-id and verify via OTP. Kindly note, a combination of OTP will be sent to your registered mobile number and new email-id. After OTP verification, a validation link will be sent on new email-id. Once you click on validation link, email id will be updated instantly in Kotak FASTag profile 2)  Send email to fastag.support@kotak.com with attached valid KYC document and dully filled and signed FASTag Maintainanence Form. Link to access Maintenance Form: https://www.kotak.com/content/dam/Kotak/Customer-Service/Download-Forms/Personal-Banking/fastag/fastag-maintenence-form.pdf