When metal is polished, it removes the surface of it to 'flatten' the surface again. So deep scratches will only disapper if a lot of precious metal on the surface is removed by the jeweller.
But alternately, if it's burnished, the metal is smoothed out to fill the scratches. Here, a highly polished tungsten tool is rubbed with considerable pressure over the surface of the platinum. The result is a high polish with no metal loss in the process.
Platinum is fairly soft so it scratches easily that's why the most popular gold for wedding rings is 9 carat. Only solutions for you (after burnishing) are to either not wear the ring except for special occaisions which is not really ideal for a wedding ring or to take care to remove it/replace it when doing jobs that might scratch it. Otherwise you will just have to accept that it will get scratched.
Yes, ask for it to be burnished, not just polished. An added advantage is that burnishing will actually result in a slight increase in the hardness of the surface of the platinum.