EXPLORA, INSTAL & DISH R1499 - SETTLEMENT OVER R4K

I was quoted R1499 for the Explora, Installation voucher and compatible Dish. I have tried to change terms from 24 months to immediate payment of R1499 3 times - all calls are recorded. All 3 times I was told that I can only change to immediate settlement after 1st debit order has been taken off my account. 4th attempt was made today and I asked what the settlement balance was, only to be told that is was over R4000. If I have not installed this device as yet, and want to pay within the next month, surely this is in contravention of 2 sets of legislation (NCA and CPA)? You cannot charge me interest and installation before it happens or before a voucher is redeemed? On contacting Multichoice DSTV today to enquire about this, I have been told that it will cost R2376 over 24 months, so how does OnAir get to over R4k? Plus, there is no installer in my area so this contravenes what was agreed to anyway and I shouldn't be charged. Surely, I get the choice to change the contract to immediate payment of R1499 which was quoted on the outset. Very misleading, which is another contravention of CPA. Asked OnAir for supervisor/manager to call back - still no one has contacted me.