Nothing. There is no way you can get your funds back especially in Telegram as we can change numbers at anytime and even put a fake identity.
So if you are victim, just say GOODBYE peacefully and say " I SHALL NEVER DO THAT AGAIN" " I SHALL NOT TRUST ANY RANDOM PERSON HERE AGAIN!"
Oh wait, you can report the channel/ group but I don't think it will be taken down, there'll only be a warning on there group (tagged as : SCAM)
other than that let's hope something comes up with Telegram.