By all means you can change the loan amount or the term you borrow over by logging in to your account. But if your guarantor does not fit our criteria then reducing the amount or changing the term won't make a difference, you will need to find a new guarantor.
We have a sister company called FLM Quick who issue loans between £50 and £500. Although they still need you to have a guarantor, the guarantor doesn't have to be a homeowner, they can be a tenant, as long as they have a good credit history.
My advice to you would be to make an application with them. Do this by going to
www.flmquickloans.co.uk and make an application.