I haven't had any problems. I went online earlier and blocked a number and a text. You must be the primary account holder to make the change. Takes 15-30 minutes for changes to register.
Log into your account > click on my preferences tab > bottom left of page under limits and permissions you have block text or block voice. If you have more than one device you will need to select which device. You can block 50 numbers or 50 text messages.
I hear you. Receiving communication from an unwanted party is never welcome. Good news is, you can block the number that is calling you. Learn more on how to on your preferred time here, http://bit.ly/1ihUVeM. Let me know if you have any other questions.
Sprint Social Care