I'm sorry to hear that the engineer booked for the weekend didn't arrive. I can totally understand your frustration. I can see that my colleague @RobbieMac has been in contact with you. There is a team dealing with your complaint and they are due to call you today.
Robbie is out of the office today but he will get in touch with you tomorrow to make sure you complaint is progressing correctly.
Had a call tonight from a helpful moderator and he has taken on my issues and will look in to hopefully resolve my concerns in the next few days.