I think the problem relates to Axchimedes principle. Not the amount of ice will have effect on the level or not.
The polar ice does not all float in the ocean. Some of them are on land. That is why the ocean water level will rise if the polar ice melt. The icebergs are part of polar ice that broke off and float in the ocean. Having more iceberg will increase water level of the ocean. The iceberg will increase the ocean to the same level, melt or not melt.