bank charges

Maintaining a certain amount in one's bank account to avoid paying bank charges

Q:

1. If I have a FNB Islamic cheque account, and when I use swipe my cheque card I get E-Bucks, can I use this E-Bucks?

2. If not what can I do with it?

3. If FNB offers clients who maintains R50,000 as balance, then no bank charges will be charged, if the R50,000 balance is not maintained then a bank charge of R199 is charged, am I allowed to maintain the R50,000 and save on the bank charges? Or is this saving interest?