claiming of excess refund due

Return for AY 17-18 filed on 31/07/2017Total TDS has been deducted ₹19750 as per salary slip and Part B of form 16(part A was not issued by employer. Form 26 also showing TDS as₹12000(₹7650 missing. After complaining to employer, employer will rectify it meanwhile you file the return with this entry. Return filed with TDS amt as₹19750,processed and refund of ₹1750(instead of ₹9400 as claimed) is credited by department to the account i. e. difference of ₹7650. TDS entry was rectified by employer in March 2018 for March 2017 with backdated effect. *Now how to claim it* as there is no change in return filed earlier as this TDS of ₹7650was included in that return although not appearing in 26As at the time of filing or setling the return by deptt