So, I accidently have sent 260 btc to the blockchain shared wallet now knowing their limits is 250 btc. According to the site, this should be returned to the senders wallets, however 8 days later this still has not happened, and no reply to my emails from blockchain.

Any help is hugely appreciated as this is really such a huge amount for me to lose.

Thank you

Theres no such thing as a 100% secure wallet, only around 99.99%