I took my roadster into a well respected Indy in March for an Oil Service and I was advised the "differential is leaking". The car went in again last Friday to have the leak sorted. I collected the car and thought all was good. I have just been looking at the invoice and it states 2 diff output seals have been replaced at a total cost of just over £300. What I don't understand is that under the Advisory Section on this invoice it states "slight seepage from Input Diff Seals". I am afraid I am not technically minded so could someone please advise me whether the seepage from the Input Seals is only detectable once you start working on the diff and if so should the work have been undertaken at the same time as the Output Seals i.e. am I likely to pay a certain amount of duplicated labour costs when I get the Input Seal's replaced. Also, does anyone know an approximate cost to replace the Input Seals. Finally the diff oil was not replaced when the work was done on Friday on the Output Seals - is this normal? Many thanks.