Blockchain is acting weird recently.
it is not new, they have always been acting weird, and always had bugs.
I've noticed that I don't receive notifications of money sent to and from my wallet
if you don't receive Email and you are sure it is not in spam folder or you are using a good email provide like Google or Yahoo, ... then contact support.
if it is SMS then it must be your operator that don't receive them, contact support and ask them to change from where they are sending it to you and it will be fixed. or contact your phone operator and ask them why they don't receive those SMSs.
and they automatically broadcast old unconfirmed transactions and then send the money back to my wallet (while my transaction is still present in the meme pool) and mark the transactions as double spend.
automatically broadcasting transactions that are not yet confirmed is a feature they have. also when you send it the first time if only one node has it then it will continuously broadcast it for you (relay).
and double spend is only when you spend it when it was back in your wallet not because of re-broadcasting.
The block height error is corrected now as I see the latest block height as 456597.
as mocacinno said, it must have been their node. possibly it crashed!