Python 2, 84 75 bytes
lambda c,a:reduce(lambda(h,m),(d,e):(d&e)and(0,0)or((h+d)%24,(m+e)%60),a,c)
Function that takes time as a tuple (hour,minute); outputs same way.
lambda c,a:reduce(lambda(h,m),(d,e):(d&e)and(0,0)or((h+d)%24,(m+e)%60),a,c)
Function that takes time as a tuple (hour,minute); outputs same way.