Not to crash the party or anything, but I dont really see why a combination of loretadine and ebastine would be of any therapeutic value, since they both work by the same mechanism, ie Histamine H1 receptor blocker.
If you are not getting the benefit that you would normally get,from your standard hayfever treatment you may find greater therapeutic value supplementing your usual loretadine or ebastine dose with an intranasal corticosteroid ( Beclomethasone), and/or ocular or intranasal sodium cromoglycate (opticrom, Optrex Allergy) or perhaps a topical decongestant