so today I took the car to a local dealer to get the brakes checked, I said that other owners have had this problem.
after 30 mins he came back to me and said it's not a recall but on the Mercedes system they have a section called "tips" which notifies him of other cars that have had this problem, He confirmed what Skeeno said and the back pads need replacing.
He then proceeded to tell me that this was not covered under warranty and I would get a bill for £400, I could see through the windows the technician already had the wheels off and had started the job, we had a bit of a discussion about this!! I said the car has only covered 2500 miles and I have had the car for 7 weeks surely this would be under warranty?! so I swiftly told him to put the wheels back on and I will be taking it up with MB customer services tomorrow.
He did add in the end they would have probably done the work if I had purchased the car from them, had a similar problem at another dealer they did not want to know as I did not purchase from them, also part of the same group I will not be using them again!!!