[NAME, COMPANY AND ADDRESS, ex.
John Smith
1234 First Street
Suite 567
Anycity, Anystate  85245] 

Dear [NAME, ex. John Smith],

I am writing to inform you of [NATURE OF DAMAGE, ex. damage to the exterior piping on our unit, #243, which results in water leakage into the basement].  I humbly request that arrangements be made for repair.  Please call me at XXX-XXXX if I can be of any assistance. 

Sincerely,

[YOUR NAME, ex. Jill Jones]