Not really any shorter, but definitely less dry and more human.

Failed Bank Import email.

Subject: Action Needed: Can't import your finacial data!
 
Hey <first name or friend>!
 
We're having trouble importing your financial bits in to LessAccounting.

Seems your login details are outdated for <insert bank name>. 
 
So, to keep your financial details spot on, we need to make sure that data gets imported.

Here's how... 
- Jump to your <link to account settings>
- Click "configure" on the account with the issue.
- Click the "Re-Authenticate" option to refresh the data connection.
 
That's all! Need help? Just reply to this email!
 
Annette
head of customer support and smiles :)

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