The greek version of file CONF_HASHORSTAR does not give the correct steps compared to the english version, ie it does not say press * to continue or # to cancel. Please correct
I don't know if the .wav file you provided is from an older version but I just checked on the current version of 3CX (16.0.7.1078), downloaded the latest Greek System Prompt, and can confirm that it is correct(the one you provided is indeed not).
Make sure you have updated the System Prompts from within Settings >> System Prompts >> Updates. If there are no updates, make sure that you are running the latest version of 3CX under Dashboard >> Information >> License (current stable version: 16.0.7.1078) and then try again.