Pending Transactions

Last year I called into the customer care because money form my account was missing , the lady i spoke to explained to me that some of the transactions take time before the they can through and i should always look at the Current Balance instead of the Available Balance (because the available balance includes pending transactions plus the actual money in my account ) which made sense to me and i have been doing that since then , Tracking the Current Balance instead of the Available Balance , and this morning to my surprise I wake up to an account which has a Gautrain transaction . on the 21 December last year I did do a transaction at Gautrain , the two people I spoke to this morning both tole me Gautrain only deducted their money on the 15th of this month , and no one can explain then how come the Available Balance and the Current Balance was the same amount , to my head that tell me there are no transactions which are pending , like then why is money being deducted when there are not pending transactions on my side ? was I being fooled when I was told to concern myself with Current Balance and not the Available balance ? I need answers Guys , this is the second time this is happening , second time its ridiculous