Product: Credit card or prepaid card

I am Citi Card member since XXXX. I am a fan HOWEVER When accessing my Citi Bank credit card account online on XX/XX/XXXX I chose the option to pay my current balance which is generated by the computer system. I paid the current balance leaving the card with a XXXX  balance. 
Ive since found charges from the closeing statement on my card and could not figure out why the numbers did not work. 
I then called Citibank for clarification. The reason they gave was due a gray area where they said that even though I paid my current balance online its really a statement balance So thats why the balance didnt include the charges after the last statement which ended on XX/XX/XXXX ... soo not a current balance?? or as the website current balance disclaimer says This is the current balance on the account today including any remaining balances from the previous statements close date. Does not include any pending or interest fees. Also warns you not paying your balances in full. Ok so then how do I know what to pay so I dont get charged. 

So the discrepancy I was complaining about were the charges ocurred on the XXXX and throughXXXX that were not included on the online current balance XXXX payment. 
Even though it says it is the current balance.and even though the statement end as the XXXX? The representative said I should be able to figure it out ... from what the limited information Citi provides listing all charges by date but not by when it actually occured ... REALLY???? impossible to figure out. 

Additionally, the system does not give me the option to pay my last statement as opposed to my current balance it does not say anything regarding differences in balances. 

I complained to Citibank clarified to them that I am paying online and not by paper. I complained about the difference experience between paper and online statements. 
The supervisor that I spoke to named XXXX number XXXX said he would forward the complaint and apologized for the misleading information on the online account. 
I called today XX/XX/2020 at XXXX and spoke to citibank for 47 minutes. 

It is so difficult to figure out because the difference between the current balance and statement balance are not clearly stated. I tired but couldnt find any information anywhere to quantify the balances shown. Impossible to figure out. 

This is not the only credit card that this is happening to my fianc also is having the same exact issues with XXXX  XXXX XXXX. 

The banks then are charging fees if we dont pay off our full balance due but how can we pay off our balance when it is not clearly stated and we have no idea what our final balances are. 

So if I pay on the XXXX I do not expect the purchases I made on the XXXX to appear after that date. 
Lets get crazy and consider if it takes the bank 4 days post a payment ( in this day and age ) is that not something that should the consumer should be made aware of? and should the consumer be penalized for that as well? How are we supposed to figure our balances out? 
Should be plain and simple not hidden or need a accounting degree to figure out. 
Since the inception of computers and programs that allow us to be responsible and pay our bills ontime to avoid fees however that doesnt make banks money and I believe they made this intentionally deceptive and confusing. 
Overly complicated policys and proceedures makig it so difficult to figure what we owe then penalize our mistakes.