I too just bought a pair of VW flats and am having trouble w/ the elastic. I don't have wooden shoe trees, hoping to break them in over time. I am on day 2 of wearing them and they back elastic part kills my heel. Got them at Nordy's and the sales girl said if they hurt too much, I could return them. How many wears should I give them as a break in before considering returning? I don't want to keep them if they never get any better but I don't want to return them if this is just a common thing that will definitely get better after a certain number of wears.