MS-Teams Message: "Usage limit exceeded. Try again tomorrow."

Dear Microsoft-Support-Team!

have an urgent matter concerning the Free Version of MS Teams:

Several employees of my company are using Ms Teams Free Version without any issues. Unfortunately now one of our employees has the problem that his account was locked due to abuse. By sending an SMS to his cell phone he could resolve the problem exactly once. But now also this solution method is not anymore applicable. Instead he receives the rror message: "Usage limit exceeded. Try again tomorrow."

Unfortunately the account does not unlock anymore even when we wait one day. Practically we cannot use MS Teams anymore.

The following solutions metzhods we tried out so far:
renewing the password, choosing a more complex password, respecting the wating time for unlocking the account

Could you please help us with this issue?

Thanks for your efforts in advance and warm regards

Susanne