I'd also try flattening the seams. I have a little wooden chopping board (small enough to only cover about the size of the iron and not varnished or painted) and when seams need flattening, I iron them and then place the board over them to tame them. Really works well and in desperate cases, a bit of steam helps the process on just fine. It is even better to leave the board on the fabric till the cooling down process is done.