I had that problem too in the past when I first started. I explained to the MSC (I think in the report as well) that I wasn't 100% sure of the exact words, but tried to replicate it from memory.
I luckily still got the shop accepted. But, the MSC never recommended a recorder. I only realized I should do this from forum members here. I bought one from Best Buy for about $35.
It's worked out well 95% of the time. Only when the environment is very noisy and a wide open space (no walls close by) do I have trouble hearing things on playback. If you get a recorder, I'd test it out in different places to get a sense of how well it picks up sound and from how far away, etc. You may want to place it somewhere on your body too that allows the microphone to pick up things easier (and also position your body towards the person talking to pick up more too if need be). You may also wish to speak louder yourself too - that might get the other person to talk louder, lol, for the recorder to pick things up.
I think my worst experiences with recorders have been at big box stores or grocery stores that are very loud (lots of people + loud music) and no walls nearby (where sound can bounce off). Surprisingly, the recorders have worked well in drive-thru fast food shops. I place it on the door handle slot, so the workers cannot see it and it picks up everything loudly usually. Recorders can be a lifesaver!