Need some advice please..

I have these slip-on-half-trainers shoes that are simply The Fave, and I wear them all the time. But they stink. Proper putrid. I had to leave halfway through the day yesterday to change shoes and spare the poor students. How can I get rid of the pong? I've tried disinfectant, soap, vinegar (I know) but nothing is working. If you know of a solution, let me know!!

Thanks =)