there is an option that "you" can freeze your funds yourself but I am not getting into that now because this is not what you ask.
It is exactly what the topic is all about
hmm! but you asked how the client can ask the wallet provider to block/freeze your money. maybe I am just confused
anyways, this is what I had in mind:
OP_CHECKLOCKTIMEVERIFY
https://github.com/bitcoin/bips/blob/master/bip-0065.mediawikiwhen it is used, it makes a transaction unspendable until the time is reached. effectively it freezes the funds for a specific amount of time. but it freezes a transaction output.
there may be wallets with this option, but the only tool that I know of is this:
https://coinb.in/#newTimeLocked