No sproing in my sprung

[Jimbabwe]

The driver's side of my bench was sinking. Had the bench out and noticed three of the flat springs right under the bottom foam were broken. Upholsterer said he could order them and an easy fix. After I dropped the bench off he got back to me and said the side spring assembly that goes from top to bottom with multiple bends was the real problem, more than the flat springs, but his distributor no longer carries them and he can not find them. He also can't find the flat springs, but says the wavy ones should work fine there. The previous owner did some hack job of bending metal to double up on the springs, but that did nothing to add structural integrity back to them.
Does anyone know where I could get the side springs, or the flat ones from? Someone said I'll need to buy a new frame, which comes with all springs. That seems ridiculous. My bench is in otherwise excellent condition. Thanks.