Lovely bargain new pair of boots - how do I stretch them lengthwise?

[soberton]

Hi
Need to ask for some advice please. I bought some lovely ladies riding style boots (low heel) in Debenhams, they are all real leather and although the size is ok, ladies size 5, after wearing them for a couple of hours I had blisters just above my heels. They were a bargain - £90 down to £25, and just what I was after, so I wondered if anyone could recommend a way of stretching them slightly lengthwise. I have tried a spray can of leather stretch but unfortunately it didn't do the job.
Many thanks