This is my fear given I purchased a second hand samsung just for this. Thanks for writing it up. Good to know I need to keep the SMS.My phone died between vouchers. I had it set to collect to the Samsung Smart Octopus. This was a bit of a mess for me:
Samsung ONLY allows to restore an Octopus provided you backed it up first. But if you back it up, is to immediately delete it from that phone. That's the only valid scenario for the backup. Backup - immediately delete -restore in new phone.
Obviously this was not my case. So I coudln't restore it. Moreover, I couldn't activate a new one until the previous one SAMSUNG KNEW IT HAD ON ITS OWN RECORDS was permanently deleted.
Then it took some Octopus forms to claim damaged the previous octopus. Any remaining value will be restored...in a month or so I think Octopus said. Then more forms to the Voucher scheme. You need the initial SMS with the scheme Ref number they sent you to fill the form (so if you didn't back up your SMS when you destroyed your phone...another catch-22).
After all this mess, they told me a couple of weeks ago, that because the way they process stuff I wouldn't be able to apply for my new voucher after they finished their processing, in Oct 17th.
...but today I already received the Voucher notification for the new smart octopus. And it collected just fine...So I guess there's that.