Shoe Crisis

I am having a crisis of sortss with my "work" shoes. I seem to have run out of old shoes to rotate to the category of work shoe. All of my other shoes are too nice, and these have seen their better day. I even tried to repair them with the magic and all serving duct tape, but I am afraid, it isn't working too well. The backs have worn to where there is a hard piece of plastic poking at my heel and shredding my socks up. I put cotton and duct tape, but that only lasts a few wearings as the tape comes loose and sticks to my sock and then upon shoe removal, comes off. I have never had a situation where I don't have a shoe to replace these. I am so lost.