Dear @amarcp ,
Please create a new sepearte post with providing more details
1- which environment are you using? sim, prod, or sanbdox?
2- which endpoint?
3- are you sure that the VAT number associated with this certificate is included as the seller company ID?
providing as much information as you can of the situation, will help us to investigate your issue, raise this as a seperate post and our team will help you.