If changing the chain rings is in order, you can certainly do it yourself. I have never needed to remove the crank to do it. It just requires a little wiggling of the rings after you detach them to get them over the arms. What you do need is two tools, one to keep the rear or inside bolt half (or nut?) from turning while you unscrew the front or outside bolt. Check and see which type tools are required for the front and back. Don't forget to specify your "bolt circle" measurement to get the right rings that fit your bike. On an Ultegra compact the correct measurement is 110 mm.