Re: So what you're saying is....
I've got a fruit cage for my Blueberries with netting completely secured absolutely everywhere, and the little sods still manage to get in.
This morning, one of our pair of garden Robins. And a passing Blue Tit (like yours, they don't actually live here - they just come for my bloody Blueberries). Frankly, I think they know how to open the cage door or something.
They're welcome anyway.