Tense (future in the past)

Two days after I go to the bank with my phone number".
Unfortunately you has to use 'later' (or 'pass') instead.
There is a strange rule in English that if 'after' is used to mentioned a time in the past (measuring from now), it is permitted to use. (PS: Hopefully this stern rule will be removed in future and people have more freedom in writing ^^.)

And since what you said must be past, you should rewrite as:
- Two days later,/passed. I went to the bank with my phone number (in mind) ^^

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1) I'm here because they/he told me to come back when I have my phone number
2) I'm here because they/he told me to come back when I would have my phone number
3) I'm here because they/he told me to come back when I had my phone number

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I think this is said to the teller. My personal style tells me "I'm here..." is weird to be used as an opening. I would rather say:
Hey. Good morning/afternoon! The teller told me to come back when I had my phone number the day before yesterday(=2 days ago).

First subordinate clause will use simple tense.
Wrong example:
I will come back when I will have my phone number.
--> Since it is clear the action of having my phone number occus in future, it is no need to repeat using future tense. A simple present tense would do.

The correct one:
I will come back when I have my phone number.

Second when you reported what the teller said, all of them were passed. We should use past tense.
- The teller told me to come back when I had my phone number the day before yesterday
--> Here instead of future tense in the past (I'm not sure the exact name of it), ie your second choice, we use simple past ie your third choice.


Hope this helps.

Hi,

1) She had arrived in Paris that morning, and she had a hospital appointment the next day. 

2) She had arrived in Paris that morning, and she would has a hospital appointment the next day.

Which sentence is correct. A is correct.

For B, you have formed your words incorrectly. I think you mean 'she would have. . .' You could say this, but it is unlikely that you would. It would suggest that the event will happen in her future, and that you know but she doesn't. eg I met her last Monday.  The next day, she would have a fatal accident, but as we spoke, she was happy about her plans for the future.

Best wishes, Clive