Audio file playback needs fixing

Hello Bidders, I recorded a Voice Memo file on my iPhone and it did not record properly. The recording was 13min 47sec and was compressed by the phone to 2min 30sec. It plays back like it is on fast forward. You are not able to understand what is being said. I have downloaded the file to my iTunes and opened a ticket with Apple on how to slow down/fix the file. Apple was unable to fix the file and told me to seek other help. We tried using Garageband and Quicktime to do it. Failed. I downloaded some other software to slow it down. Failed. The file has been slowed down but it still sounds like high pitch gibberish. The file is now an mp3. I still have the original file on the phone and the original file downloaded onto my iTunes. I need a sound file EXPERT to fix this file, if it's even possible. I need this done ASAP! Thank you.