Not getting approval notification on my phone number

I want to set up my deposit method on sellercentral when I click on add new deposit method it asks me to select marketplace when I select marketplace then it asks to approve the notification sent to my phone number but I am not getting any notification on my phone number despite resending it many times. I contacted seller suppot but they say you are from a country not supported by amazon. I am from Pakistan and Pakistan is also on sellers list. I also tried to change my phone number to new number to get notification on that number but new number is also not getting OTP. What should I do now