You could get some of the skills you need for this job by doing a Level 2 or 3 Diploma in Customer Service. This will be useful for dealing with complaints and mediation work.
You'll usually need:
- 2 or more GCSEs at grades 9 to 3 (A* to D) for a level 2 course
- 4 or 5 GCSEs at grades 9 to 4 (A* to C) for a level 3 course