such an old app @Moulinsky why not try a newer one like SpamBlocker (Call & SMS) | F-Droid - Free and Open Source Android App Repository
or NoPhoneSpam | F-Droid - Free and Open Source Android App Repository
also, when making accusations, it’s helpful to point where is the source code the bad behaviour is done: GitHub - kaliturin/BlackList: Blacklist Blocker is a free Android application for blocking unwanted calls and SMS