-What does 'with' mean in the first sentence? Should it be 'about' or 'with regards to' or 'concerning', perhaps?
-'Could you send it back' implies the writer has sent it to the person he addresses and asks him to return it. It sounds more like the writer is trying to say 'Could you send it to me again'.
- The original text is quite truncated and I'm trying to guess the background. There is here an implied story, about some Mayor Zaharos or the Mayor of a place named Zaharo, I can't know. Indeed 'concerning' could apply, I'm not very fond of 'about' though, as we have no indication the whole thing is **about** him. And 'with regards to' is too high-pitched compared to the rest of the message.
- OK with your proposal, I understand the difference of meaning and you're right, but it doesn't seem so critical to me, once again only significance is asked for. For the sake of better English, your sentence might be fitter indeed, go for it