Invoice not being emailed...AGAIN!!!

Over the past couple of months I have had to phone customer care numerous times to email my monthly invoice. The process is always the same, I phone them wasting 30 minutes of my life waiting for an operator. Every single time they promise me the problem has been rectified and they give me some idiotic excuse of why it happened and without fail it just happens again, this is about the 5th occasion that the same problem has occurred. I am sick and tired of phoning them every single time for the same problem. I will never ever refer this network to anyone nor will I touch this network when my contract eventually expires!