Whether you're shopping for groceries or looking for a car, you want options. Shopping for a mortgage loan is no different. And there's no better place to find options for a mortgage refinance than with a mortgage broker.

One of this summer's blockbuster films is the Fantastic Four, a movie based on the adventures of four superheroes. The quartet's leader is the genetically altered Mr. Fantastic, who can stretch his body like silly putty. Mortgage broker often use powers similar to the costumed crime fighter. They can stretch and shape a mortgage refinance to fit your financial situation.

Here are five reasons that explain the unique superpowers of mortgage brokers, along with a word on how to prevent a broker from stretching your refinancing budget past the breaking point.

1. One broker, many lenders. Mortgage brokers can put together a variety of loan packages because they have access to a wide range of lenders, who operate on a wholesale basis, relying on the brokers to find customers. A myriad of lenders operate on this basis, and brokers can choose whichever program fits your needs.

2. Superior access. A wholesale lender works only through brokers. As a result, consumers don't have access to their special programs or rates. You need to work with a broker if you want access to wholesaler's unique loans.

3. Stretching that loan package. A broker doesn't have the constraints that you might find at a bank or credit union in terms of structuring a deal. They can stretch or limit their fees and the terms on the loan. More flexibility on the part of the originator means a more flexible loan for you.

4. The ability to be disloyal. A mortgage broker doesn't need to be loyal to a vendor. If you're unhappy with a particular lender or don't like the package it puts together, the broker has the freedom to look elsewhere. Wholesale lenders understand this, and they do what they can to keep the mortgage broker happy.

5. Third party flexibility. The same flexibility brokers have with loans also applies to third-party vendors, like appraisers and title companies. Brokers can shop around until they find the best prices with the best quality work-and they can move very quickly.

For all their flexibility, mortgage lenders do have their downside. Because it's relatively easy to become a mortgage broker, many don't have extensive training or knowledge in the industry. They also derive much of their compensation through fees, so you'll need to keep a close eye on your Good Faith Estimate. Be sure to ask for references and check with the Better Business Bureau before signing on with one of them.

If the broker proves to be established and reputable, let her put her fantastic powers to work. The result should be a refinance that makes a mortgage broker look like a real superhero.