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Water infiltration from an elevated water level below the floor is a difficult matter to solve, at least inexpensively. The solution is to drain the water from under the floor to a sump pit, and that generally means installing perimeter trenches and drain tile below the floor level and tying it to a sub-level sump pit.

I agree that your problem would not be resolved by a waterproofing company. Your walls are not transmitting the moisture and waterproofing them would not significantly alter the situation, you would still have infiltration from below. Lowering the water level involves cutting a trench along the perimeter walls (actually along the inside edge of the foundation footer) and installing drain gravel, perforated drain tile, more gravel over the top and finishing with concrete. The new drain system terminates in a sump pit. This kind of work is labor intensive and involves a lot of concrete cutting (dusty) and excavation of dirt and concrete, then replacement of drain materials and concrete. When completed, as water rises, it should flow into the drain pipe (at least 1-foot below floor level) and never reach the floor level. The work is complicated if there are sanitary pipes or water lines imbedded or below the slab. The resulting drain system is similar to what would be installed in new construction before floors are poured.

An alternative may be, if you know the direction of sub surface flow, a curtain drain can be installed outside in a deep trench and kept dewatered using a pump, or if there is adequate slope, gravity. This is a lot like the cone of depression created by a water well. The trench stops horizontal movement of groundwater towards the structure and acts to lower the local water table. If the trench is not placed correctly or has inadequate capacity, you will still have water. The advantage to curtain drains is large excavating equipment can be used in place of hand labor, and the work is outside your home.

Call foundation and drainage contractors for estimates or bids. If you need assistance in design or evaluating your specific groundwater problem, a geologist or soils engineer can probably assist. A test boring can even be done outside to determine the height and variation of the local water table as well as soil permeability and related engineering information.

All the above assumes you have done everything possible to divert surface water away from the foundation so it does not contribute to the water table below the house.