Nike Air Pegasus

I'm hoping someone has had this problem and can give me some advice. Bought some lovely nike air pegasus whilst on holiday worn them for about 3 miles. Have been out of running due to injury, seen a physio who says I need to wear stability shoes and not to run in the pegasus. They are as good as new but unable to return to shop as at the other end of the country and bought the middle of April. Is there a good way of selling these shoes or do I have to just put it down to experience? Ladies size 6 if anyone is interested!!!