Poor customer service

I have been waiting for my sim card to be delivered for the past 3 weeks. I made a booking for delivery and sent a message that it would be delivered the following day between 12-5. I waited till 5 pm no one pitched or even a call to explain that they had a problem or running late. I've been calling them to ask when are they going to deliver but still nothing. What irritates it's that i have to phone and beg them to deliver. Today after waiting for 3 weeks I was told that I have to wait again and it will be delivered next week on Monday.