Highlighting text in a column- a different colour for the amount of times it is repeated

I have a list of peoples names in column C, their names are inputed the first time they use the service and repeated if they use the services provided again.

I want to highlight them depending on the amount of times their name is in the list.

The most is 15 repeats at the moment but it will be increasing.

I can then filter by colour, if needed, to find out who has used the service regularly

Thank you

Add column next to it and use =COUNTIF(C:C, C2) (assuming data start in 2nd row).
You can use Conditional formatting by that column and you can also filter them by number (rather than color).