Customer paying invoice into old / unused bank account B2B

[uber]

We had an old barclays account which we used to use before switching to Hbos and its only purpose now is being used to pay off the old overdraft we had on the account. When we switched banks and cancelled the overdraft the bank set up a monthly payment to clear the remaining balance.

Last week one of our customers decided to pay their full invoice total into our old account even though the invoice clearly stated our banking details , bank account and sort code.

I called Barclays and they have said they just see it as a payment to account and its went towards the overdraft.

Any ideas if the company who made the payment can reclaim the money and try and get it back so they can pay our correct bank account (Both business accounts)? After the terrible service we had from Barclays I really dont want to fast track the deal we made with them