blockchain.info shared receive question (missing coins) 0.25BTC bounty

[BTCVanc]

Recently had a transaction sent to my wallet via the shared receive address you can generate. Unknowingly to me the payment was sent in chunks, and the shared receive feature is only good for one transaction. I can see that the entire sum (60btc) was sent to the shared address, but I was only delivered approximately half.

Im curious how this plays out? Does blockchain.info just keep the rest, is it sent back to the issuing wallet? Is it eventually sent through to my destination wallet?

0.25BTC bounty for well informed answer.