Open a blocked account for rental guarantee locative

Hi,

We are about to rent an apartment in Brussels, and have a problem to do rental guarantee locative.
I am ING client, but at the moment, ING refuses to open a blocked account for me.
I contacted with KBC, but they said if only for guarantee locative, they will not do it (though, on website they say they are willing to support even when you are not a KBC client).

An alternative way is to opening of such an account through the Belgian government via the following link:
https://financien.belgium.be/nl/borgtoc … aarborg#q3

But this way, apparently, the guy from agency does not agree because the owner now is living in Germany. He proposes KORFINE.

As I read info from internet, apparently people do not trust KORFINE, because the info they provide is not clear, and has some problem of returning the deposit when the contract is terminated.

Do you know other ways to do rental guarantee locative in Brussels?

Thank you