w202 brake switch limp mode problem

Hi There. I have a 2000 W202 C240 sport. For over a year now the BAS and ABS lights have been showing. I don't drive the car much so kinda ignored it. Recently the car went into limp mode with the brake light and engine light showing. First my nearest Mercedes franchise changed all my disk pads. That never helped. They then changed the brake light switch even though and that never worked. The thing that is confusing is the car does not show the brake and engine light (limp mode) when cold in the morning and only later when it gets warmer. The Mercedes mechanic suggested there is a communication failure between the computer box and brake light switch because the diagnostic report still shows the brake light switch to be faulty. They want to charge me for 7 hours of investigative work. This makes no sense to me because my lights are working and it works in the morning. Please could you assist in what the problem could be?