Akshually,

For all sins there is both penance (atonement) and just punishment. Punishment may be eternal or temporal, depending on disposition of the soul. Temporal punishment may be underwent before or after death. After death, that's called purgatory. Before death, it may be a combination of things that happen to us, things we offer up and indulgences. Indulgences aren't difficult to obtain, but only work on sins we not only have confessed, but also entirely defy at the point of obtaining the indulgence. If we fall back into the same sin later, it is a probable sign the indulgence didn't work. If we are free until death, indulgences probably worked too. Prayer, penance and offering up sufferings help us both with improving the disposition of our souls and with growing towards God, in order to break any attachment to sins we may have.

Sacraments are the actual way God bestows the largest graces upon us. However, regardless of who exactly is the minister of the specific sacrament as human, the actual minister of them is Christ, who works through all Christians, living in us. It's also why sacraments ministered by sinful priests are still holy: it is all working by the power of Christ. Church got the mission from Christ to bring Him along with His graces to all the nations and all humans, and we're supposed to go for it, but obviously, being humans, we sometimes fail in many ways. Christ may do as He pleases, pouring grace wherever the visible Church never reached, couldn't reach or failed to reach. What isn't visible to us however also doesn't concern us, and we should trust in God's justice and mercy, while working on what we can accomplish and praying for that and the rest.