Remove all the bedding from your pillow-top mattress: pillows, sheets, comforter and sheet cover.
Locate the zipper on your pillow-top mattress and unzip it to open the pillow top. If there is no zipper, use a stitch unpicker to remove enough stitching to gain access to the pillow top stuffing.
Relocate the lumps in depressed areas of the pillow top and/or remove the lumpy stuffing to make the pillow top smooth and even.
Zip up the pillow-top mattress or sew thread to close it up with a needle.
Replace the bedding covers.