Reliability, as it concerns you and your business, is all about systems. Component and sub-system reliability is a concern insofar as it affects system reliability. System reliability is what ultimately drives the relationship between business outcomes and operational performance.
System reliability modeling will obviously be as complex as the system itself. Modeling does more than relate component reliability characteristics to system performance: it gives you an understanding that can let you improve system reliability. System reliability modeling is also useful in the design phase when all you may have is component level reliability characteristics.
Acuitas can help you in your system modeling needs. Acuitas has expertise in many modeling methodologies that can be applied to a range of systems: a range that will almost certainly include your systems.