I know of some ladies that use conduits instead of their poles, they were purchased at home depot/ Lowes and cut to length. Perhaps if you take a pole with you to get the right dimension then you are sure you have the right part. It is not uncommon for people that quilt a lot to have to replace their poles on various frames. The bend in the poles particularly the center of the pole is cause by over tensioning the poles when loading quilts. I just load my backing, then drape my batting and front over the back. I secure the top with a doing a line of stitching and then the other end I use white plastic C clamps to keep the quilt straight. If you are able to get two good poles you might be able to float your batting and top and use the poles that are not bent. Good Luck
jane