This deal was handled terribly by the GoDaddy employee.
First of all, it sounds like she encouraged you to create another Afternic account. That was unnecessary for the deal to happen.
By the way,
@Igor Gabrielan can you confirm that the first contact was through email and NOT Afternic platform.
Because if you were contacted via email or your website, then they really screwed you.
Secondly, the broker should have advised you to change the Nameservers to Afternic before the deal was finalized. Especially if the domain name was not actively listed on Afternic in the first place.
Thirdly, what exactly was the purpose of opening with an offer of $20k and then including a valuation of $270k?
That's basically making an offer and then including empirical evidence that your offer sucks.
Also, the buyer definitely had MORE money to spend on the domain name.
Finally, you agreed to a gross of $25k. Even though you did so based on a misunderstanding of the message, you still did so.
Gross = Total payments from the buyer.
Gross = Net + Commissions.
The misunderstanding here is due to language barrier. Even though the broker handled the entire deal in a terrible way, it doesn't seem like they were being intentionally malicious.
This entire problem stems from (broker's) incompetence and (your) misunderstanding.
Fact is you don't write like someone who can't immediately tell the difference between Gross and Net. And the broker likely had no reason to assume that to be the case.
Especially when you confirmed in a second email that you were willing to accept the $25k gross offer.
I hope GoDaddy resolves this in a way that favours you. But next time, make your desire CLEAR by stating that the $x amount is what you wish to RECEIVE in your account.