Need help converting text to date for merging date entries

I have retrieved credit card statements from my different cards and try to merge these into one sheet sorted on date.
However, one of the banks seems to be exporting the date field as a text (at least that's what I assume to be the problem). At least it seems so since I don't manage to make the dates from this provider sort and merge in the list.

EDIT: I added an attachment. The file shows all 3 cards entries (first 2 columns) in the same sheet. Card1 stays at the top unsorted and card2 and card3 merges and sorts (see bottom of list).

The card company which seems to use text-dates is in blue and when I click one of the dates the window showing cell values doesn't change. Another trick which I learnt here on the forum (pressing CTRL-SHIFT-~ ) should result in a number in the cell value window. This doesn't happen. Pressing these keys still shows same text/value. So I'm assuming it is just text.

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The card company (in orange label) that seems to give me real dates look like this and will give a number in the cell-value window when pressing CTRL-SHIFT-~ .

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I prefer dates in the list to be in the dd.mm.yyyy format.

How can I change the textdates for the first card company (card1) above (in blue labels) to real dates so that my list will merge and sort like card2 and card3 does? (see bottom of Excel file)

Regards
B