How fast can you fix a broken Magento checkout?

Emergency checkout-down issues get a first response in under 4 hours on a retainer or emergency ticket. A single, well-defined bug, rates not showing, totals not updating, agreements blocking submit, is typically fixed in 24-48 hours end to end. Deep root causes spanning several symptoms run on the Bug-Fix Sprint, usually within a few business days, because we reproduce and regression-test rather than guess.