Can’t get rid of vertical lines

There is a band of multicoloured lines an inch wide running down the left hand side of my iPad mini screen. It obscures the display beneath but touch still functions.

I asked support for help and it amounted to backing up then doing a factory restore. It has not worked. Any suggestions?

If even a factory reset didn't help, then it could be a hardware issue. I think you'll be best off going to an Apple Store with your iPad or sending it in for repair.