3 yrs post op Eyebrow hair transplant, my new eyebrows doesn't look natural. Is there any way to fix this?

A bad eyebrow surgery is permanent, but you can always pluck out the eyebrow hairs you don't like.  There is no way to fix it.  Only other way may be to remove it and do another surgery.

It's always a good idea to get advice from the hair transplant surgeon who did the procedure - a call, email or fax is recommended. In general, there are three options for someone who does not like a transplant outcome:hairs can be removed. One can pluck, laser the hairs. This needs careful discussion with experts in laser surgery but can be doneHairs can be camouflaged by tattooing the area.  This too needs to be done by experts but can look great when in the right handsNew finer hairs can be added to the area with another  transplant. Either the old hairs that are too thick can be removed or newer finer hairs can be strategically placed into the area. There are many options, as you can see. Touch base with the original team and take your time consulting with several experts. 

I wold have to see what the problem is to determine if something could be done about it to meet your needs, 

It is tough to make an eyebrow transplant look natural, even in the best surgical hands, and so it would be expected that if you do only one brow, it might look a bit different.  The first thing you should consider is getting in touch with the surgeon who originally did the transplant.  I know you are in different countries, but they may have some ideas for how the appearance can be improved.  You can also consider electrolysis (or laser hair removal) which can sometimes have the even nicer effect of making the hairs grow in finer - and thus looking more natural.  In some cases, if the hair is really too thick to manage, you can laser all the previous transplant away and fill it in with much finer hair that looks more natural.  Even a tattoo can look natural and might be a good alternative to additional surgery.  Definitely try training the hair to lay as flat as possible with either
brow gel or wax and pluck the ones that are the most problematic until
you decide what to do about the overall appearance.Good Luck!