Message AT+SBDWT sent automatically after a callBack() false exit

Hi Mikal,
thanks for your cool library... it shortened to me a lot of developing trapping SBD comms back and forward...
By the way I have an issues... I used the callBack() FALSE exit to abort and override a transmission if there is a condition to override it but in any case the library send an AT+SBDWT text message over the network.
How can I block this?
Thank you in advance
Clay