Poor workmanship and very shoddy work

LemonThorn undertook a complete repaint of my house 18 months ago, and gave a guarantee of 12 years on the paint and 5 years on the work. The workmanship was shoddy at best, the paint was the left over from someone else's job (found the labels) and the paint has already peeled from many areas of the house and many areas require a complete redo. The same is applicable inside the house, where paint is blistering in the same places it blistered before, and paint on doors has s****ped off. Frankly, I don't even want them back to fix the mess.