Start with My almighty madam.
This will grand enough.Kidding.
Dear sir/madam :
Thank you for supporting ABC at all times--First of all, we want to tender our thanks to you for your great support to ABC at all times.. As celebration of *** Opening, a cocktail party will be held on 20th May 2007 at 7 P.M.-- we are looking forward to seeing you at our cocktail party which will be a celebration of *** at the same time ... on Level five at ***.--- We invite you to attend the party with deepest sincerity. Further, a “*** Signature Rewarded Card” will be issued on upon showing this letter on the night.(I didn't understnad this sentence) It will be our pleasure to have you attended.---- We will be gratefull if you can attend our party.
Yours sincerely,
ABC
This is my try.