Debris on M25 blew out tyre so pulled onto hard shoulder. Truck behind me carrying loose large stones must have also hit as my car was then showered with large stones (which have dented back of car). Called mercedes assist at 3.40. (Covered by them) Called back at 4.10 to say with Rac as priority (woman on own, m25) rac say be there in half hour. 5.30 call from rac to say v close but not sure where exactly I am. Despite being given info from road signs which exactly pinpoints location. By this point it is dark and am frozen! 6.10 get call from someone to say just been passed job and will be therein half hour! Which he was - from mercedes assistance. Reckon rac person gave up. No update about this from them. V dangerous and scary on M25 in dark plus cold and drizzling and phone running out. only got to mercedes as husband kept phoning rac and couldnt get through so rang mercedes.