D.L. Mitchell Landscaping, Inc

Continual grass/weed problem after completion of work. Contractor says it is normal.
Mitchell performed rock landscape. Work is fine,but continually have weed/grass coming up through the mesh block. I have spend $125 within first month of work to try and stop this. Contrator says this is normal and will help if I am will to pay extra. The initial cost for all of this was $10000, which is pretty high. I also would have appied a double layer of weed/grass block prior to applying the rock.