Bank pays out monthly standing order twice

dunstonh

They messed up my voluntary NI payments by typing my NI number incorrectly.

They told me that they could not fix it (a simple typo). I had to cancel my direct debit with HMRC and have HMRC issue another one.

Direct debits are controlled by the originator (HMRC in this case). Not the bank. Santander wouldnt have typed anything in. HMRC would have and HMRC could have corrected it easily.

However, its irrelevant as the OP says they used standing order and not direct debit. The two things work differently.

Why they cannot do it? It's bank mistake. I think you must take an action. They are fully wrong. I am with you. You must be write an application for correct this big problem. I think this may be happen in future again. So resolve it now. Quickly.

How have you been able to make that assessment when there has not been enough information provided yet to decide that?

The OP said they set the standing order up online. Not the bank. Duplicated payments could occur due to one of three things:
1 - an amendment was made to the standing order within 2 working days of it being paid. That is too late and can often result in two payments being made (original and amended one)
2 - OP set up two mandates in error.
3 - the final payment amount was set to a higher figure than the regular payment amount (although that would not result in two payments but one payment of a different amount)
4 - bank processed the batch twice in error (that would result in a more widespread issue affecting many people).

If the OP didnt amend the instruction just before it was due and can see that two instructions were not set up then you are looking at a bank error. A bank error should be corrected by the bank.