Hi @Welshdragon1957, sorry to hear about this. 
Is the line always shown on the display or is just on certain backgrounds or in certain applications?
If you go to Settings > System > Advanced > Developer options and turn this off, is the line still shown on the screen? If it is, get in touch with your Local support team so they can arrange a repair for you because in that case, the screen is defect.
Keep me posted!
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