A CAT IIIC approach is one with 0 DH and 0m RVR. The problem with this is that it would be a problem exiting the runway after landing and finding your way to the parking stand. Even CAT IIIB approaches can have a 0 DH but usually have a minimum touchdown RVR requirement of 75m.
The 17ft DH that Taraman quotes sounds like a MABH. This is the minimum RA value that the aircraft manufacturer has established that the aircraft would not touch the runway in case of a go-around initiated at that height.
17ft is incidentally the MABH for the A320 equipped with CFM56-B engines. The IAE powered A320s may have a different MABH value possibly due to different engine acceleration performance, but I stand to be corrected.