If your bank won't let you open up a merchant account, consider using an Independent Service Organization. You can contract with the ISO to open a merchant account, and the ISO will contract with the bank. The ISO, in effect, bears the risk of doing business with you.
Of course, the ISO will charge you for its services. Be careful here. Although there are more than 1,400 ISOs in the U.S., they are not regulated. Make sure that you understand all the extra charges before you enter into an agreement. Sometimes you can be grossly overcharged for the equipment the ISO provides you , not to mention other hidden charges.