The quantity and levels of service that IT is able to provide are always bounded by the associated costs. IT Service Level Management (SLM) is tasked with helping the customer understand the tradeoffs between cost and benefit. This should be accomplished in a way that allows the business to make decisions about which services it requires and what levels of service are justifiable, given the current business environment.
In organizations without strong SLM, IT is often left making these business decisions even though IT does not have clear understanding of the business environment and its drivers. This results in frustration on the part of both the business and IT as the business feels powerless to make service decisions and IT feels that the business is ungrateful for its efforts.
Implementing SLM has additional up front costs. However, those costs can easily be offset by the benefits derived from IT and the business improving their working relationship. If it is important to IT to be seen as a strategic partner to the business, then it is incumbent upon IT to demonstrate that fact by allocating resources and management commitment to both an SLM process and an SLM Manager.