Standard Bank Cell Phone day light *******

I was called 4 times by Standard Bank Agent wanting to give an cell-phone contract; i was not keen on the Standard Bank Cell phone contract; in that I already have one with the another provider. Then I was told that it is R49.00 month and I essentially be my monthly service fee back in airtime of R490 monthly at no additional costs I then agreed and I was told that there will be a once-off payment of R99 which fair, was fair enough, now they are debiting my account monthly with an amonot of R490 a month and was told it will be for 24 months even if I leave Standard Bank I will still be liable for it; I mean that is too much as I didn't even get any device. I really didn't agree to this charges i was taken for a ride, I will inform other people run away from this bank it is bad news