Good qualities, unfortunately cut unpleasantly

First of all: The shirt has absolutely fulfilled its purpose! I habs bought for a cross-country steeplechase, to carry it to the Neo. It has kept warm and it has not passed also scratches or Aufschürfungen that have occurred at the knees and legs (without corresponding long trousers).

But I got the shirt, already knowing it to carry over it, appointed in L, though I usually wear M. Compression shirt well and good, but it is clearly too tight and was there already a little too long. It is supposed to be tight, all right. However, under the left shoulder hats cut and hurt after four to five hours, the seam is in my opinion simply stitched too tight, right, the problem is not aufgereten.