Upgrade costs an tax-number

[CoachLena]

Hi, i want to upgrade m y account but everytime i want to buy the product, its telling me to enter a tax-number, despite i try to use it private. 

THen i switched to my Phone, seems like im Able to buy it in there, but only for 30 EUR more than with the laptop. 

Can somebody help me with these 2 Problems? 

Thanks!