there is a samsung shop which repairs tablets and phones in al barsha area. It is v close to the sharaf DG metro station on the al barsha side. the shop is called Technocare and is specifically for samsung. I dont have a telephone number but if you know the service road that runs parallel to sheik zayed road on the al barsha side then it is quite easy to find. i got a phone fixed there and they were quick and efficient, the only downside is that they were a little bit expensive compared to the satwa/karama shops that seem to fix phones but i think it is always better to go to a dealership.