Apple wallet loyalty cards vanish

Suddenly several loyalty cards have vanished from my Apple Wallet. Just tried to add the one from Boots from their app but it will not let me as it says the card has already been added to wallet. Yet it is no longer there! It was there until last week when some of these loyalty cards just disappeared. Looking at expired cards they are not there either so it is completely mysterious what has happened and how to get them back????? I am having to use an old iPhone 7 after my 13 Plus Max was stolen (last spotted in Dubai on Find My) and have not yet been able to get a new one so have lots of issues as there seems no support for old models.