You should be able to change your PIN from the locked screen of the app using the ‘Forgot PIN’ option.
STEP 1:
Click on "Forgot PIN" 
STEP 2:
Enter the OTP sent to your registered mobile number
STEP 3:
Now, enter the PIN sent to your registered Email id
STEP 4:
Set a "New PIN"
STEP 5:
Confirm the "New PIN" by re-entering the PIN
STEP 6:
Now again try to login with your New PIN. If the error still persists please a ticket with us.
NOTE: On resetting the PIN, the withdrawal will be disabled for 24 hours for security reasons. You can retry after 24 hours.
If you are not able to regenerate your PIN like this, please raise a ticket for your concern.