Delays and excuses

It is the first time I use Sureglass. I had a frameless shower door installed - after waiting for more than 10 days on the promised date (with no communication from the sales department unless I made the phone call) and many excuses, cancellation at the last minute, the installation team eventually came. But they couldn't finish the installation because the step of the shower is not level. Something they should have checked when they came to take the measurements... So now I have to pay an extra R500 for the installation to be completed... when is the next question!!! Why can't companies get their act together and surprise their customers with a job well done and in time????