I often come across lists of SLAs with KPIs with the thought that measuring everything will result in better customer service. This idea is still prevalent in the government sector in particular. However, the opposite is true. This approach often creates a rigid and inflexible attitude between parties, which certainly doesn't improve the customer experience.
Allow each other room to make mistakes, but also to do something extra to improve the experience, without immediately holding each other accountable. Of course, there needs to be a solid foundation, but the rest should be done through open and transparent communication and mutual agreement, understanding what is happening and what really matters for the business. You'll see that this results in the best customer service.
Is this topic of interest to you? Do you have relevant experiences, ideas, or a different opinion? I'd love to discuss them with you.