Yes it is true, they do make acrylic tub liners. But I think you will find most people here will recommend to replace the tub. Many tub liners have a problem of trapping water between the existing tub and the liner itself. Although if you can find them, there are companies out there that do offer a custom molded liner for your tub and do a good job installing them, and also proffesional tub refinishers that can give you a quality job with a warranty. The problem is finding the true proffesional that does a first rate job out of all those weekend hobbiest that are doing the same thing and not using quality materials or good workmanship.
My opinion,, change the tub.