Carson Slip-On Sneaker (Women)

I love the way these shoes look, the color, the heel height. I just can't figure out a way to keep the right shoe on my right foot, so I will probably need to send them back. The left shoe fits my left foot fine. But, even with heavy socks the right shoe keeps sliding up and down off my heel. The first time I wore them the right shoe kept catching my long skirt in the heel as it slid up and down. I tried to put a spacer inside my sock to make it stay in place, but that wasn't very effective. I don't want to glue anything in the shoe because I will need to send them back if I can't find a solution to the extra width of the heel space. I have been wearing Vionic shoes for many years and never had this problem with any of them before. If anyone at out there knows a solution, I would love to hear about how to fix it.