PayFlex or PainFlex

A simple task of changing a cellular number has been an absolute nightmare. I need to change the cell number in order to receive the OTP from PayFlex and they still asking me to verify the OTP being sent to the old number. I have logged more than 5 tickets on their website, as they do not have a contact number at all. they only deal via email. Still no luck, they have changed the number on my personal details side on my account, but the OTP still goes to the old number.... Makes no sense at all