Have you applied for your visa yet?
I know it's been a while since you asked this but since they don't require you to add the loan letter in the package you can just have them fix the problem for you while you wait. It takes them like 6 days for them just to open the package so I'm sure you could have this problem fixed by then so that in the case that they do ask you for it, you are ready to show them the letter with the correct information.
My timeline was as follows:
Applied online July 20
Biometrics Appointment July 23
Package received July 24
E-mail of package opened July 30
E-mail of Visa Issued August 10
This is (obviously
) not priority processing.
Let me know how it goes!!