When I bought my M4 last year, it had some finance owing on it. So I paid 5k via credit card to the finance company. Then I did a bank transfer for the remaining amount owed to the finance company. Then I had to do another bank transfer for a lower amount to the seller for the difference between the 2. 3 hours later we have been to the sellers bank to see where funds are, I have rang HSBC (my bank) 3 times to check the payment to the seller has gone through and all 3 times they confirmed it has, and there was no issue there end. I asked about if security / fraud team had flagged it, and was told no, nothing stopped by that department and the payment had gone through so the holdup was with Natwest. The seller is on the phone to Natwest again, there saying nothing showing on there system. Then 30 mins later my phone rings, HSBC Fraud dept, just wanted to check that I made the payment. I confirmed it, but then questioned why it had taken them so long to check the payment and why did they stop that payment and not the larger one to the finance company done 5 mins earlier. They said because it was to a personal account, that it might have been fraudulent and wouldn't say anything more. Then said all security checks were done and the payment would be in his account in 2 hours (so 5.5 hours in total from when the instant transfer was made). I put the phone down and said to the seller, they just told me 2 hours for payment to go through from now, but if you check it will be in your account now, and it was.