automatic gearbox repair for peugeot 207 sport how long should it take?

i recently got a peugeot 207 sport on finace from a garage and was given 3 month garentee. i drove the car a number of three times before gearbox fualty came up on the dash board took it back to the garage its been there from 7th april and its been two weeks im not sure if this is the correct amount of time, also everytime i ring it seems like im being fobbed off can anyone get me advice?