Do you have to use the Merc Dealers? any garage will do the service properly provided they are VAT Reg, ask them to use the Gen Merc parts this will not effect the resale price, & also get your service book stamped by them, regards your tyres, If you have the time, search around but do not use K.F. they may recommend you need a new engine, for a full Merc service I would think you are looking in the region of £200>>£300! am I correct? for a family run garage you can half the cost.