Mice and rats are very hard to control if there is a food and water source for them. The first step is to eliminate water and any form of food that is exposed, even crumbs. Thorough cleaning is important. Next eliminate the access. Stop up all holes, cracks and crevices where the rodents would have entry into the house, office or whatever. Repellents can now work. Try fox urine, hot pepper dusts and sprays. Live traps sometimes have to be used, but the best control is still - cats!