You would need to review the document which explains what is needed to cancel the transaction. That said, the legal concept of the "mailbox rule" may still apply. In general terms, the rule states the date you place the letter in the mailbox is the date your letter is effective.I purchased PP on October 13th. Decided we didn't want them so sent a letter certified mail via USPS on October 17th. I have the receipt and certified paper. I've been following it on USPS...they sent it from Orlando to Naples so I put in for assistance. Someone from Orlando post office called and left me a message saying the machine read the zip code wrong which was why it went to Naples but they realized the mistake and it's on its way to the correct address. I had contacted them on the 26fh and they called me on the 30th. Today I tried calling and no one picks up so the message literally says "goodbye" and hangs up on you. I put in a second request for assistance and got an email this evening saying my claim was closed because basically, they can't help me. Sums up saying, they can't track my mail...that's not what certified is for (it should've been "certified and registered" if I wanted it tracked). Sounds like they have NO idea where my letter is and don't seem to care. I have proof it was sent...is this enough for Hyatt? Not sure what to do...should I call and explain? If anyone had this issue and can offer advice I'd really appreciate it thanks!