price lock a way to de***** customers

i got sold the explora ultra on price lock for R549

guys came to install few days later all was well but couldnt catch up so viewed the app to see if anything is wrong there was an amount R110 and some cents that i need to pay, i did that and the services got activated immediately, few days before my first debit order im told i will pay R862.57 on top of the R110.32, i called in to find out why my bill was so high first lady said its a system error and the correct amount of 549 will be debited on the 25th, which wasnt the case they came and took R862.57, called them again to ask what changed, again another agent said its a system error so next month my bill will be R313.57 less because of the extra charge for this month. credit went unpaid because thats not what we agreed on. now i call again to have them debit their R549 im told i need to pay R962.99 the lady i spoke to yerusha said she will log it with their billing department but theres a pro rata amount i should pay which was never discussed, i think dstv is using the price lock as a way of having access to our bank accounts to de***** us on monies we never agreed on, im really unhappy id rather they come get their explora put me back on my old decoder and i continue paying the way i did because debit order isnt working they just de*****ing me