First Merc (W203)

[numberstation]

Hi there. I have recently bought my first merc (2002 W203) and the first problem that has come to light is the parking break does not release and often takes a few different goes to work. I see from elsewhere that this is a common problem and one solution seems to be accessing the section underneath the rear seat and tighting up the cable. Can anyone confirm this is correct? and if so what exactly needs to be done? Some people talk about spraying WD40 in and others just tightening it up and other boards say don't touch this.

Also, I bought the car from a 2nd hand dealer who gave a 3 month warranty. Next service not due for 9,000 miles but would like to have someone look over it to see if there are any major issues whilst I still have some recourse to the dealer. What should I ask for at the dealership and is it worth going to an MB garage? I see there is a 'peace of mind' service offered for £40 but not sure if this is what I need.

Any suggestions much appreciated.
Thanks
JC