Third party pop ups, screwed because I have a tablet?

Been having Securitte pop ups for Walmart gift cards take over my screen when I'm in ebay. Read where they are gathering info on you. I can remove their top, smaller pop up by using the back button, but can only get rid of the full page one by exiting my screen and going back in, I'm using a tablet. No place on their page to exit or do anything. Been going on for almost a week. Checked out a number of links, none worked, finally read where I can't stop these because I use a tablet. Anything else I can try? Not a computer geek.
Duane