Santander 'Double' Standing Order Payment

[supermac9]

I've just learnt a lesson with Santander - don't try to amend a standing order within 24 hours of the payment date or they will pay it twice!
A couple of days ago, I went online and amended a large monthly (variable) standing order (I reduced it by £10) - however, yesterday Santander paid this standing order twice, one for the higher amount and the other for the one with £10 off. This has been a major problem as it has stopped my mortgage standing order going through - I have explained this to my lender (not Santander thank god) and will put this right today.
The recipient of the two standing order payments has sent confirmations through that both were received yesterday.
As a final note, the larger of the two amounts has been refunded to my account this morning.
I wonder what they will do to me next!

[supermac9]

Re: Santander 'Double' Standing Order Payment

Update.
The credit back to my account is from Santander's own funds as they are unable to claim back the money from the company they sent it to - it looks like it is up to me to organise getting the money sent back, presumably to my account (and Santander can then take their credit back). All a bit messy but at least I'm not out of pocket, although they did try to charge me an unpaid standing order fee for my missed mortgage payment (they have agreed to cancel this)!