You can choose yourself where to set up your blocked account. It is important that the following conditions are met:
The blocked account must have sufficient credit in order to cover the costs arising for the duration of your planned stay in Germany, unless other proof of financial support is presented in the visa procedure. Certain standard rates apply (for students, the presumed annual requirement that must be paid into the blocked account has been increased to 10236 Euros).
The account may only permit the withdrawal of a certain amount per month (increased to 853 Euros for students).
The blocked account may only be closed with the consent of the blocked account beneficiary. The blocked account beneficiary is either the mission abroad or the competent foreigners authority. A blocking notice therefore only ensures that sufficient funds to cover living expenses are always available. It does not entitle the blocked account beneficiary to withdraw money from the blocked account.
You are free to choose a provider. Worldwide providers you can find via the following link on the Website of the German Federal Foreign Office.