I've just received a thank you card for a gift I didn't buy. It was for a little girl's birthday and I had sellotaped the birthday card to the gift so that they would know who had brought what when they opened them later.
Anyway the mother has sent a lovely note all about how the gift is her daughter's new favourite toy and how did we know she loved that (er, we didn't) etc etc
Would you let her know about the mix-up? (Presumably the sender of the fabulous gift has received a note thanking them for ours?!) Or just let it go?