ERROR on Adobe echosign

I'm trying to receive a Bounce Back Loan from natwest and they are sending me echosign documents for signature. Once signed and returned to them I'm getting a document back from natwest saying I've entered the wrong sort code for my bank account. I haven't. I've tried now five times over the course of 3 days and natwest agree it's an error with Adobe echosign. Apparently they are investigating it. Need it done ASAP though as natwest not coming back to me with solution.