I would like to repeat this same question: Can anyone answear that:
What is the longest password (I mean with how many characters - big/small letters + numbers + symbols) that you can crack?
Before you start bruteforcing can you check how many characters have password?
Technically, The length of the password can't make the brute-forcing impossible. It only makes it longer.
As the OP said :
If it's uncrackable within 48 hours, I will return your fees.
And it's also impossible to know the length of the password before brute-forcing.