Extremely poor customer service

My name is Bongani Mthimkhulu and I have an account with DSTV. I have a Compact package and on the 15/04/2019 I made a cash payment of R400 to reconnect my DSTV as there were no payments for the month of Feb and March... So today I went to Shoprite to make a payment for this month and I was told that I need to pay R1 544!!! I called Multichoice Call Centre and I first spoke to Thabo, who told me that I had two decoders that were active and I asked him how come because I bought a new one last year October. He was *********** and told me that I need to take it up with the installer, who funny enough was provided by DSTV, so I hung up and called again... I then spoke to Sphamandla who had no clue what he was talking about, lacked product knowledge and he even put me on hold for more than 10min on a 23min call. I also hung up because he put me on hold for a very long time... If a DSTV provided installer, installs a new decoder for you and even calls on your behalf to activate your new decoder and does eveything for you but doesn't deactivate your old decoder, who's to blame? I really feel I'm being taken for granted by this company!!!!!