Faulty decoder on price lock plan and pathetic after sales service

On 21 Sep, I had the Explora ultra installed after signing up for price lock. Since then I have had issues with viewing and I have sought out assistance by contacting the Dstv Facebook team and I emailed ***. Since installation of the decoder, when I switch on the tv there is sound but no picture. I have to reboot the decoder and the picture comes back but there is no volume. I then need to change the channel and I have sound again. This is a waste of my time and not how a brand new decoder should perform. Furthermore when I reboot I lose the memory on the decoder so I cant go back and watch a program that started 20 minutes ago, for instance. This defeats the purpose of a decoder with PVR functionality. When I emailed a lady contacted me but when I went back to advise that what she suggested did not work she ignored me. I am paying over R1000 a month on Dstv so I really expect better. Do I need to get my bank to reverse my debit order for me to get assistance? If that is my last resort I will get the debit order reversed but I would rather this problem be resolved!