Useless windscreen wipers on LEAF

Do you think they are replaceable under warranty? It's in for the first service next week, so I can see what they say. I certainly think it will need two new front tyres. Though they have fared slightly better than yours, I've got 12,000 miles out of them!

I'm wondering if it's wax causing the problem? I used Muck-Off split second wax a few weeks ago, on the body but wind was strong. I tried taking the wiper off today and cleaned it with fairy, in a bid to shift any oily residue. I manually used it on a window and it worked fine. Starting to think I may need to thoroughly clean the windscreen.

Thanks for the replies. I had new wipers fitted under warranty at the first service last October as they have always been poor. The new ones are slightly better but still streak. It is not often parked under trees, so it's unlikely to be sap, and it is really just the drivers side wiper that smears. The dealer stated that the problem is where the blade contours to the windscreen. I may try changing the washer fluid, but if it doesn't improve it will go back again especially as it is just in line of sight.