Guarantees only come with Guaranteed Networks:

There is no magic dust that eliminates network problems.  There are great efforts, with good tools by trained, available, and motivated personnel.  Our Guaranteed Networks(TM) service makes your IT issues our problem.  We will maintain your network and help you derive real business benefit out of it for an affordable, budgetable, fixed fee.  When something breaks, it costs us, not you.  We've shifted the incentive.  That's why the customer always wins.