Very inconsiderate attitude and behaviour towards their client

I had an appointment with them for an installation of a chlorinator. The appointment was made, agreed upon and fixed for a certain time (first on the list for the day), but they did not honour the appointment time. After I had to plan my day to be at home at a certain time to meet with them to do the installation (organise with my workplace, etc.) , they took it upon themselves to change the time without consulting me or informing me of the change. Apparantly the installer "changed his planned route". Had I not phoned in to find out what was going on, I would have been left in the dark and I just would have had to accept their inconsiderate behaviour. And then the person in the shop has the audacity to say to me that they are really sorry for the inconvenience caused. Ag please, really!? If you really were sorry you would have acted professionally and stuck to the agreed-upon appointment time, or at least have contacted me in advance so I could have re-planned my day. Needless to say, I had to make alternative arrangements so they could come and do the installation. I am really disappointed in their attitude and behaviour towards me as their client. Very unprofessional. This is a BIG let down!!