change
c1.companyrefid = (Guid)reader["CompanyRefId"];
to
c1.companyrefid = reader.GetGuid(reader.GetOrdinal("CompanyRefId"));
OR
c1.companyrefid = new Guid(reader.GetString(reader.GetOrdinal("CompanyRefId")));
if you not getting guid values from web service client side, try by adding below attribute to web service class
[AspNetCompatibilityRequirements(RequirementsMode=AspNetCompatibilityRequirementsMode.Allowed)]
reference:
WCF service service returning GUID fails with VB.net c[
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