This story is typical of the difficulty people have in managing their finances well. The real problem is that banks and card companies have little interest in providing detailed analysis of financial information to their customers. As well as the divided nature of those institutions in that any one will only see a portion of the situation.
Firstly Banks, so my bank has all of my direct debits, and standing orders, and they know pretty well when and how much those are. They could project that forward and show me a projection of what my balance will be at the end of the month, next pay day or similar.
Card providers generally only show cleared transactions, sometimes there is a special display for pending transactions. This may be an important distinction for the Bank, but not to the consumer. As soon as I have made the transaction I want to see that in a statement.
What I want is at the point of making the decision, to have the information to make that decision. Can I afford to buy this thing this month or should I wait till next month. In the simplest case.
A more detailed analysis would be for the longer term. Like am I maintaining enough savings to cope with a not having a job for a couple of months, perhaps there are rumours of a takeover at my employment and I want to increase this target. Give me feedback on how many months before I can achieve that at my current spending / saving rate.
Personally I do this myself, and have done so for many years. I use GNUCash to record all my transactions. This allows simple reconciliation with statements. Then by ensuring that standing orders and direct debits are entered in a month before they are due I have a good projection of my future balance.