Ideal Blinds

Some of my 10 year old shades had cords that were fraying and breaking so I had them all restrung. My bedroom shade worked great, but I was afraid the cords would break, so had it also restrung. That shade stopped working soon after it was restrung. The cords twisted and one side always got hung up so that I had to physically pull that side down every time I shut the shades. The service person came out, but refused to restring the shades. He said that the window was too big for one shade and it would never work. I reminded him that they worked just fine for 10 years before he fixed them, but he still argued with me. What good is a company that doesn't guarantee it's work?