Many companies offer short term, small (under $10,000) loans. I worked for WF for 8 years and their service area for this is actually separate from the "big" bank and called Wells Fargo Financial. Other banks offer similar services: CitiFinancial, Capital One...
Wells Fargo did, at one time, offer unsecured lines of credit within their main consumer bank. I have one from about 12 years ago that is for $5000 and it just sits there to serve as overdraft protection. I drew against it for a home improvement once, and paid it back within a a few months, and I remember the payments being about $100 a month. It was paid in full within a few months, just like you are referring to. I am not sure if they still offer this type of Line of credit, due to the current lending environment, but you could check. I'm quite certain that credit guidelines for this type of thing will be very strict, if they do still offer it inside the bank. Your terms may not be as favorable, but I'd bet credit guidelines will be less stringent in their WF Financial side. Typically, these types of deals don't take a week to process.
You should note that Lending Tree (The Lending Club, lending.com, etc.) is NOT a bank. They are a lead generating company. Banks, or individual brokers can sign up with them, pay a fee, and get your information sent to them. I'm not saying it's bad, just know what it is.
Hope this helps!
C.