undisclosed additional charges on account

On the 29/01/2015 i paid my monthly subscription of R298.00 as per the statement i received. on the same day i went to festival mall to exchange the decoder i was then referred to Randburg multichoice offices where i met a lady who assisted me with changing the dcoder to an Explore decoder, when we were there with the lady we asked her what is the total cost required to change to the Explore she said we will have to pay R1699.00. we then asked her is it the total cost for everything she said yes, my husband and i asked the lady about three times if the R1699.99 is the toatl cost she said yes there is no additional costs except that on our monthly instaltment we will have to pay an additional R75.00. on the 6th my services were disconnected and when i called the call centre i was told i owe multichoice, i asked how come and how much i was told i owe R165.10 which was due to a R99 for smart card and R75 for additional services. i'm very unhappy that when i was at their offices i was not told about these costs and now they have to take me by suprise in the middle of the month. i feel that i did wrong to change cause now there is hidden costs that were not diclosed to me. very unhappy.