If you do not wish to go for the thermal reconditioning method to manageable hair, you could try this tricks instead and hope hair over a period of time, becomes soft and manageable.
Always rinse with the coldest water you can stand after using a shampoo and conditioner if you want rain straight hair. The cold water "locks down" the hair cuticle and makes hair appear slicker, less frizzy.
Use a weekly home remedy-a "hair mask". Mix one egg to one part mayonnaise and one part olive oil. Make a paste and apply to hair. Warape hair in a towel and keep it on for atleast 30 minutes. Rinse out and shampoo and condition as usual. Hair will have a smooth and shiny appearance.