If your cat’s fur is so badly matted that her movement is restricted then she is in pain when she moves, and this undoubtedly decreases her quality of life. If this is the case, then I think you must have her coat clipped or shaved. If sedation is the only way that this can happen, then you must seek medical advice to see if she is up to sedation. If not, then there may be a specially strong shampoo or soap which would help to dissolve the matting if you are willing to repeat the wash several times and she is willing to be patient.