My attorny stopped his check refund?

My Granddaughter need an attorney and we went to see one. He charged $3500.00. We decided that my Granddaugter is not capable of supporting her child so we told him we would not need him. He refunded me for unused time. He wrote me a check for $1300.00 and than he stopped payment on check. He really overcharged me for him service's. What can I do