Study permit validity error

[GKO851]

I got my intial study permit for the validity of only 4 months the first time i arrived in canada. So i have to apply for study permit extension but the validity of extension was also 4 months. I am enrolled in a two year program. So i contacted ircc through their toll free number and they said there was a error and they have made request to case office to recheck my file. But there is no answer from them it been one month. Does anyone know how much time ircc take to make corrections.