Then you have to get rid of the VO & VO_Signed fields in your query. They have unique values that is throwing off the
Group By:
SELECT tblPhase.Phase_No, tblPhase.Roads_Bond_Received, tblPhase.Roads_Bond_Ref_No, tblPhase.Roads_Adopted, tblSite.Site_No, tblSite.Department_Number, tblSite.Name, tblSite.Designer, tblSite.Agent, tblHouse.House_No, tblHouse.House_Address, tblHouse.Town, tblHouse.House_P_Code, tblHouse.House_Type, tblHouse.Gross_Floor_Area, tblHouse.N

f_Apartments, tblHouse.Number_Of_Bedrooms, tblHouse.Garage, tblHouse.Agreed_Price, tblHouse.House_Price, tblHouse.Deposit_Received, tblHouse.Deposit_Amount, tblHouse.Remaining_Balance_Paid, tblHouse.House_Stage, tblHouse.Electricity_Meter_Reading, tblHouse.Gas_Meter_Reading, tblHouse.Water_Meter_Reading, tblHouse.Plot_Depth, tblHouse.Date_Of_Entry, tblHouse.House_Handed_Over, tblHouse.Building_Warrant_Ref, tblHouse.Date_Building_Warrant_Received, tblHouse.Full_Completion_Certificate, tblHouse.NHBC_Registration_No, tblHouse.NHBC_Registration_Date, tblHouse.[%Complete], tblServices.Date_Made, tblServices.BT_Reimbursement_Claimed, tblServices.Sewer_Reimbursement_Value, tblServices.First_Drain_Test, tblServices.Sewer_Drawing_Ref, tblServices.Sewer_Design_Approved, tblServices.Sewer_Adopted, tblServices.Sewer_Reimbursement_Agreement, tblServices.Reimbursement_Recieved, tblServices.Service_Ref, tblServices.Phone_Reimbursement_Amount, Sum(tblVariation_Order.VO_Price) AS SumOfVO_Price, tblVariation_Order.Date_VO_Paid, tblCustomer.Title, tblCustomer.First_Name, tblCustomer.Surname, tblSolicitor.Forename, tblSolicitor.Surname, tblServices.Service_Type
FROM (tblSite INNER JOIN (tblPhase INNER JOIN tblServices ON tblPhase.Phase_No = tblServices.Phase_no) ON tblSite.Site_No = tblPhase.Site_No) INNER JOIN (tblSolicitor RIGHT JOIN ((tblCustomer INNER JOIN tblHouse ON tblCustomer.Customer_No = tblHouse.Customer_No) LEFT JOIN tblVariation_Order ON tblCustomer.Customer_No = tblVariation_Order.Customer_No) ON tblSolicitor.Solicitor_ID = tblCustomer.Solicitor_ID) ON tblPhase.Phase_No = tblHouse.Phase_No
GROUP BY tblPhase.Phase_No, tblPhase.Roads_Bond_Received, tblPhase.Roads_Bond_Ref_No, tblPhase.Roads_Adopted, tblSite.Site_No, tblSite.Department_Number, tblSite.Name, tblSite.Designer, tblSite.Agent, tblHouse.House_No, tblHouse.House_Address, tblHouse.Town, tblHouse.House_P_Code, tblHouse.House_Type, tblHouse.Gross_Floor_Area, tblHouse.N

f_Apartments, tblHouse.Number_Of_Bedrooms, tblHouse.Garage, tblHouse.Agreed_Price, tblHouse.House_Price, tblHouse.Deposit_Received, tblHouse.Deposit_Amount, tblHouse.Remaining_Balance_Paid, tblHouse.House_Stage, tblHouse.Electricity_Meter_Reading, tblHouse.Gas_Meter_Reading, tblHouse.Water_Meter_Reading, tblHouse.Plot_Depth, tblHouse.Date_Of_Entry, tblHouse.House_Handed_Over, tblHouse.Building_Warrant_Ref, tblHouse.Date_Building_Warrant_Received, tblHouse.Full_Completion_Certificate, tblHouse.NHBC_Registration_No, tblHouse.NHBC_Registration_Date, tblHouse.[%Complete], tblServices.Date_Made, tblServices.BT_Reimbursement_Claimed, tblServices.Sewer_Reimbursement_Value, tblServices.First_Drain_Test, tblServices.Sewer_Drawing_Ref, tblServices.Sewer_Design_Approved, tblServices.Sewer_Adopted, tblServices.Sewer_Reimbursement_Agreement, tblServices.Reimbursement_Recieved, tblServices.Service_Ref, tblServices.Phone_Reimbursement_Amount, tblVariation_Order.Date_VO_Paid, tblCustomer.Title, tblCustomer.First_Name, tblCustomer.Surname, tblSolicitor.Forename, tblSolicitor.Surname, tblServices.Service_Type
HAVING (((tblServices.Service_Type) Like "Phone" Or (tblServices.Service_Type) Like "Sewer"));