Not getting service am paying for from Multichoice

I have been calling multichoice for months now explaining to them that my secondary decoder some channels that am paying for are not playing. I did what was asked of me hard reboot, cabling, and taking my decoder to the multichoice offices and it was tested and no fault was found. Today I called again and agent gave 3 a number that I must call for dstv installers but is not working.