Refund not credited

Dear experts, I filled A. Y 2020-21 ITR 15.12.2020. ITR PROCESS 3 MARCH 2021. AS PER ITR & as per intimation order refund determined. But refund not credit in my account. Refund status show No record found. Bank account already prevalidate. View return file tab show "process with refund due" 3 March 2021. I submit three four time greevance. But there r no response. I submit 4 time greevance but there r no response. I call toll free number. But pan number and date of birth wrong said. No response from call. Please suggest and SHARE ANY MAIL ID FROM RESOLVE THIS ISSUE.