Happy to report that this was resolved very quickly after posting here. A dell representative private messaged me through this forum and got it fixed.
I placed an order on the 20th of August 2022, and on the 23rd of August I got an email saying that "due to an unexpected error, your Dell Technologies order [44039736] has been cancelled and cannot be completed". It also said that "any authorization will expire within 7 days maximum". However, the sale amount keeps getting re-authorized every time it expires. This has been happening for 11 weeks.  I've been in contact with my "account manager" since the 23rd of August, but I haven't had any response in over 5 weeks now despite the problem still being ongoing, and despite his manager and one other person being copied in on every email. Most recently, I emailed with new screenshots showing the new authorizations still occurring on the 10th of October, 20th of October, 31st of October and today, the 8th of November, but have had no reply. Is there any way to escalate this, or to complain about my account manager, or to just get the problem fixed?    
Bank account authorization repeatedly occurring for 11 weeks and counting