207 Brake Light Problem

Hi new to the forum. My wife has a 207 CC and it has a problem with the brake lights. Sometimes they work and sometimes they don’t. Sometimes they flicker

it’s all brake lights including the high level

I have changed the brake light switch twice and still have the same problem

if you pump the brakes it sometimes starts to work and with the switch out of it’s fixing points I can get it to work most of the time

it doesn’t appear to be adjustment

I have noticed that some replacements come with an additional small wiring loom, is this because there is a known wiring fault ?
Also I have seen a thread that suggests it is caused by a bad earth on the rear lights and any help on that would be great

sorry that m6 first post is for help, I am reasonably capable but this is making no sense.
Thanks for listening

Geoff