MCD is Air Med, based at London-Stansted & Oxford with some Piper Senecas,
MCS is indeed the Greek airline Macedonian Airlines, a subsidiary of OA
as for SWL, it is not Air Namibia which is NMB, but I believe it is a Scandinavian Fokker F-27 operater, but I can`t remember the name right now.
Maybe someone else can help here??
PS: Do you have a routing (origin/destination for these flights?)