Get him to take a look at this. It states it requires 5 years reference check so must have been at work part time or full time for this period. Basically he needs to do a job in customer service for 5 years and have a record of his service etc.
Show him what they require and he can go about having the experience they require when he applies.
Good luck to the lad.
https://tuijobsuk.co.uk/job/72192/TU...r-2020-Bristol