Netflix complaint: Not happy

I have been using Netflix for the past 2 years now. I do wonder how many ppl really pay attention to there billing, I’m from south Africa and we pay R139 per month and this is the second deal on the list now what I do not understand if u pay whit ur card u only pay R139 per month but when u go out of ur way and u get I gift card to try and save up some money for a rainy day u pay R150 per month and I dont get how this is possible because the package are a fix rate and not any additional money is supposed to be paid so for the last 2 years I was under the impression that the R11 that u save ever singel month will be there for u to use so today was today was the rainy day that I was saving up for not wanting to go to town I wanted to use my credit that I have been saving up for just to be told by a rude online help center man that Netflix do not keep credit it gets used up. But how if my fix around is less then the amount I put in so supper confused and whit no help from the rude man I tried again to get help so I tried again and was told that the R11 gets used for the remaining days for the month and that no matter what u will never have credit. Now how doze this work? if u pay from the 21st till the 21st that’s one month so where is the extera days that he is taking about? So I have lost R264 in 2 years I’m R14 short then I can had 2 more months payde for but thy just take the money.

Can some one please explain to me?