Heel slippage is related solely to width. You sound like you're trying to fit a square peg into a round hole on the 5 last. I'm not sure why so many people think that they can just alter the size and have it work for them. Read: http://www.allenedmonds.com/aeonline/SizingView?langId=-1&storeId=1&catalogId=40000000001 5 Last (65) This is the longest in length of all of our lasts; best for a long, narrow foot. Does that describe you? If not, then you should have bought something else. Put them on ebay or B&S as Quad came, try to recoup most of your money, and then try another last or another brand.