FNB seems to endorse Digital Planet who accuses a pensioner of lying when a broken TV is delivered

My received an offer that she is eligible to purchase a device which was ordered. This was a Hisense Smart TV. Upon delivery, when my Mom asked what she must do, they told her "Sign here". She is 87. They did not try and assist with checking the contents in the box. They did not offer to help check that the item was intact. We have now been told that we damaged the TV which is not true. What defense do we have now? The emotional trauma my mother has experienced with this transaction is unacceptable. The box was not damaged, there was no indication that there would be a faulty TV in the box.