Hi Chris, how old are the fabrics? years ago (10 years +) this was a big problem with fabrics, which was mostly down to polycotton mixes, the new age of curling is more often than not down to cheap fabric, as customers we all want a better deal, as blind makers the only way to give you the better deal is to cut down on costs, ie you buy cheaper. You can usualy spot these fabrics by thier hard feel and they are not very thick,the chances of getting them straight is Zero. The best answer is to replace just the fabrics with a quality fabric.
John
October 2007