Personal use call recordings

This has me a tad unsure, and curious on views...

Someone on the internet said ...

... that it is better to not use a call recording when making a complaint or dispute. Why? Because you can "legally only make the call recording for personal use".

Well, yes, first off, GDPR related, "personal use" is a thing that takes stuff out of  GDPR. But it is also possible to make a call recording as someone registered with the ICO under GDPR and comply with the rules and use for something else. After all, the call centre you are calling does that. But I fully agree, that would be unusual for someone personally making some sort of complaint. So yes, it would be for "personal use".

But then, surely, "personal use" must cover "having a record of what I said and what was said to me", and "personally using that in a court or with an ombudsman" - is that "personal use"? Maybe, maybe not, I really do not know.

But then... I could definitely make "personal use" of a recording to "aid my memory" in making a transcript of the call - nobody else hears the recording, only me. And making a transcript of a call is something I can legitimately do with, or without, a call recording, yes? The fact that "I made this transcript using a call recording to aid my memory so as to ensure it is 100% accurate" has to carry a lot of weight with a court or ombudsman. Indeed, if the other party claimed my transcript is wrong, it starts to be accusations of fraud, and I am sure in such cases a recording could then be used to validate the transcript, surely?

I also seriously doubt a court or ombudsman would ever exclude a call recording anyway. The other party raising legal objections that the recording should not have been made would rather hurt their argument as it is "we only said wrong things because we thought you would not have proof of it". Of course if a court or ombudsman said they won't accept a call recording, you just say "fine, here is the transcript I made, using the call recording to aid my memory" (perhaps even with an oath of its accuracy) - they are going to accept that - so the call recording has been useful.

I also find that simply saying "I'll check the call recording" is a hugely powerful phrase, and you don't even need the recording most of the time!

However, this then got me thinking of the alternatives suggested.

Email - keeping a record of the emails sent and received. I 100% agree this better, but not based on "not being able to use a call recording". I can take my time composing an email (I fail to do that some times, sadly). I can avoid losing my cool, etc. But then so can the other party (and they may have more training and practice).

My thought here is: how exactly is a record of an email exchange any different, legally, from a record of a spoken exchange. Why would one be "legal" and one not? Surely they hold the same "personal information" (if any). Does GDPR differentiate between them? Or is this not GDPR but something else? Surely the record of emails is just as much only allowed for "personal use"?

And how is that different than taking a screenshot of an "on-line chat" (another suggested idea). This even has the fact that the other party cannot simply assume that of course you have a copy (like email), as you had to actively make a copy, without asking.

And really, how is this different from old school written letters?

I am curious to know - where is the line drawn, why, and by what law?