A bit of a revelation here, which has solved a mystery about some PBs we bought.
About 2 years ago, I gifted money to my DH in PBs. I added (what I thought was) his PB unique number onto my iPad app so we could check our numbers together, and for the past couple of years we've been doing our normal thing of checking the App every month.
I've won a few prizes over that time, but DH has never won anything, which kinda felt strange as I would have thought £15K would have won even if it was a £25 prize.
Meanwhile we noticed a few times we were receiving what at first glance looked like a genuine advice into our family email account (probably about 4 times) saying DH had won a prize. Because the App was telling us he hadn't won anything we convinced ourselves it was a scam so we deleted the emails. I'm always particularly cynical, DH just shrugs, he leaves all that stuff to me 
Yesterday, for some reason I thought I'd try adding the PB app onto my Samsung phone. Added it, then entered my PB unique ID and got the Lovely Lady Quaffing Champers as I'd won the prize in January. I then entered DH's PB number and ...... drumroll..... up comes the LLQC!! £50 which was a nice surprise.
It then occurred to me, hmmm maybe DHs PB number was wrong on my IPad. Checked and yes it was the wrong number so it wasn't picking up his winning numbers. Goodness knows which number I entered, it wasn't his NS&I number and it wasn't his PB number, I had entered a mix of alpha numeric. Silly me. Anyway I checked our bank account and thankfully we had set up his account so any winnings from both our accounts were credited to our current account. Difficult to have picked up whose winners were whose, as they just add a long convoluted reference on the credit plus PBZ. In all we had £50 in July and another couple of £25's from his numbers, but hopefully with the increased allocations of numbers maybe we will get lucky.
It did solve the mystery of the very convincing PB emails saying he had won, because he had!
Moral of the story, when downloading the app make sure you check that your entering the right number, because the App doesn't tell you "You've entered an unrecognisable PB number" it just accepts whatever you enter, and you're none the wiser, which is actually a bit rubbish. I bet it doesn't integrate with their database to match IDs.
I might ring them today and let them know as the other rubbish thing is that to get the complete list of your winnings beyond just "Last6 Months", you have to logon to your account and we tried numerous times but it just took us back to the logon screen, none of the normal "you've entered the wrong password" nothing, just back to the beginning. Grrrr.
NS&I get a Nul Points rating from us for their IT systems! Too many convoluted steps, NS&I number and separate PB number (confusing), poor error handling, poor logon experience for accessing user account.