Worst customer service and problem shooting procedure.
I was paying for someone else's bill for 6 months as my direct debit was registered to another person's account. I had to repeat myself to explain what was wrong to 5 different people, being transferred over and over again. I always need to give myself an hour+ to talk to the customer service team on the phone. Eventually took me a week to finally talk to someone who knows what went wrong and can get the money refunded.