Its not just about the value of the modifications. The insurance company may regard someone who has made certain mods as a 'boy racer' and a higher risk which I'm sure the OP isn't
I'm 76 but have not personally received significantly higher insurance premiums over the years apart form this year when my renewal will be 30% higher but I understand this is a trend over all age groups.
There are several Ford days at the British Motor Museum in Warwickshire also over the next few months which may be of interest. What's On at the British Motor Museum
Its calculated on mileage and number of days since the last service. It is possible your service indicator was not set correctly at your last service.
If you start to book a service online and the car was previously serviced by Mercedes then the date and mileage of your last service will be...
Home (Robin Lamb)These are in Gloucester and I have used them and had good service.
Also but in Cheltenham
MB&B Ltd – Independent Mercedes Specialists These have good reviews but I have no personal experience
I had the same problem and MB diagnosed a new cluster required. The quote was £1400 but MB paid half as the car was only 4 years old.
I hope your problem is battery related.
OPs car is petrol so wont have a DPF? I didnt think catalytic's regenerated as such but I may be wrong. I've read that they continually burn off deposits.