If you are sending your concerns to WGT support, it might be back logged. I have always had my issues solved quicker through trialpay support, who actually take care of these offers.
Under earn free credits there is a support tap on the right had side, click that, find the offer you mentioned above and follow the links through that particular venue.
If you have been doing this, then I am sorry to hear you are having these issues.
cheer,
b0gey