This is your chance to shine and show Sky Bet exactly how you excel at providing customer service. Think of a time when you've helped a customer and they've been effusive in their praise afterwards, think of a time when you've provided such a great service that you've wanted to highlight this to your peers, your manager and anyone else.
Link this to the fact the role plays into the strengths and skills you possess, as that's likely why you're applying in the first place. Attraction to the role, not the wage or benefits, is why you'd like to join.
I was honest, that's important, you have to show not only a weakness you identified, but what you did to improve yourself. Example: high hold time, identified and decided to look for the answer to the customers' query while trying to talk to the customer instead, using less hold overall and building a good rapport with the customer.
I answered using a particularly stressful example in my previous role, making sure I included the actions I took, who I liaised with and the end result; whether good or bad. The key here is to show that you can deal with difficult situations to the best of your ability.