Indulgences have been long deemed sinful.
You cannot "pay" to have your sins removed quicker.
Come on guys, lets be better.
You need catechesis on indulgences, badly.
1) An indulgence is not the removal of sin. That is known as forgiveness and takes place within the confessional or with perfect contrition (for mortal sins); for venial sins it can take place in the same manner, or through prayers and pious acts (Our Father, crossing oneself devoutly with holy water, receiving Holy Communion, etc.). A person in/with mortal sin cannot gain an indulgence.
2) Though a sin may be forgiven, it still merits a temporal punishment
3) Temporal punishment can be remitted via works of charity (broadly speaking); the treasury of these spiritual gifts come from the merits of Christ's sacrifice on the Cross, and the Saints who made satisfaction beyond their own debt. Because the Blessed Virgin Mary was sinless, and spent every moment of her life on earth gaining merits, we are especially indebted to her over all creatures for the gift of indulgences written in the blood, sweat, and tears of her prayers and good works -- themselves made possible in the foreknowledge of God of her merits in light of the Cross and as begun at her Immaculate Conception. To put it simply, our good works/prayers are actually from Christ, primarily. Having done them, we become closer to Him, and thus less like "ourselves" -- the condition of our fallen nature which precipitated the sins to begin with.