Here is a Sample Apology Letter for Inconvenience. You should modify this apology letter according to your need and situation.
I hope you would have reached your residence. I am posting this mail as soon as you have left my home. And I believe that this mail might reach you prior to you reach your residence since I am mailing this post through the express postal service. I am doing so because I am in the need to express my heartiest apologies for all the inconveniences that you and your family members have felt during your period of stay of 5 days in my residence.
The heart of the problems which pushed you and your family members into inconvenience whilst staying in my home is the power problem in our street due to the burnout of the street transformer. It might seem to be a lame excuse. But really it is the core factor for all of your silent miseries.
In this modern era, living without electricity would bring up a lot of tension and pressure to the inhabitants of the regions without electricity. You and your family members are well educated people and have lived in a well equipped and facilitated residence. I was the one who forced you to stay in my home during your period of visit without taking rooms in private hotels. But it was purely accidental that only on the date of your arrival that our street transformer had exploded. I thought of it would be repaired within 2 days and requested you and your family members to kindly adjust just for 2 days. But it didn’t happen as expected.
Hope you could understand my helpless situation and accept my apologies.
With Warm Regards,