What do you mean by warning?
CPS wouldn't normally deliver a police warning?
is it possible you could scan and email the letter?
You are in Scotland which explains the difference.
I will opt out and move this to Scots law for you.
I'm a solicitor in Scotland. It appears the wrong offence has been put into the letter. Notwithstanding the time for appeal has expired you should tell them by replying to the letter that they have got it wrong. They'll then issue the correct letter. Happy to discuss further.