Faulty decoder

We have a problem with our explora, from day one it gave us issues. It reads that the disk is full, even when there are no recordings, every month we have to format our decoder, and lose all our recordings. I went to the customer care, and was informed that i can format or swap the decoder or purchase a new one. My problem is, WHY do i have to pay R600 for a decoder swap, when we have never had joy with this decoder from Day 1. I just want this decoder fixed, it's not my fault that it has issues