I am sorry you had a difficult trip, starting with the loss of your luggage--I have hosted enough people to understand the stress of travel and how that can spoil a break.
1.) With regards to your comments, you reported a problem with the fob to enter the building. I arrived within 30mins. to give you new fob. I still don't know why it stopped working, and it is not a problem we have had before. These things are sometimes sensitive to large magnetic sources.
2.) You asked me how to use the timer for the hot water to which I responded immediately. I didn't hear back from you until the day before your checkout--you said you were too busy to get back in touch. On being told you still had problems, I sent out an engineer, who checked and reprogrammed the system.
3.) On the day of your checkout, I received a call from AirBnB because you had asked for a refund of your entire trip based on the problems you had. I have since sent AirBnB a transcript of all our communications, and they have closed the case as a result. I should add that no guest before you or after you has reported not having hot water. For large groups (6+) there is a chance that the tank empties and can take 30mins. to heat itself up again, but this is not unusual for flats in London.