Struggling for a month to replace decoder

I Went to the multichoice branch in Benoni a month ago as my DSTV Explora 2A hard drive is *******. They refreshed the decoder and informed me that if it gives me the save error I need to replace the decoder. The next day it did the same thing. I went back to them and they told me that they do not have stock, but will call me when they do. In the mean time my decoder is now so damaged that I'm unable to watch anything. It freezes and reloads every 10 min. Unable to watch catch ups and not even recoding any program. I've been struggling for a month now to swap my decoder. The excuse every time is that there's no stock - phone next week. I even contacted other brances - Edenvale, Kempton Park and head office with the same excuse. We do not have stock. I'm paying for a subscription and insurance and can't even use it. What must someone do to receive a new decoder. They are quick to take the R1000 per month, but not even trying to assist when there is an issue