Two way voice on any of the cameras just dont work for me

I have spoke with customer support twice,,they were nice and tried to help, I have added the wifi extender and placed it in the best place for best connection,,replaced the doorbell once (free replacement) However no matter what I do,,move cameras, move extender, replace doorbell,,,the two way voice does not work,, I can hear through the cameras but neither one ( I have a doorbell and an indoor camera on the back porch ) will allow me to speak through it,,,not what I paid for...I am ready to toss the whole system and get a different one,,, I really like the alarm and the system but these cameras have left a bad taste in my mouth,, so to speak..If anyone has any other suggestions please advise!