What document/journal should one use to write off debt as irrecoverable?

If the supplier follows the below publication,

Then the question is, How should you write of customer's irrecoverable debt?
If you use a credit note to write off the debt as irrecoverable and to use it a supporting documentation when you claim the Output-VAT back from SARS which you paid when you issued the original invoice, then I assume you would have to send the credit note to the customer to inform them that they would have to repay the Input-VAT which they claimed from SARS on the original invoice which you issued them.
Therefore this Credit Note would make the customer think that they don't owe you the money anymore.

However as the above Link publication states, the write off of the debt as irrecoverable does not release the customer from the obligation to pay the amount owed

Any further clarification would be much appreciated