After 6 months of topping up the oil on my second hand E90 318i I have just noticed in the service invoice from the dealer that there are 2 serious problems that they failed to tell me about.Sump Gasket leaking oilCover Gasket leaking oilAccording to these guys they renewed the timing belt and Head Gasket prior to sale which helped the deal, now I'm stuck with these major repairs 6 months later.What do you suggest? It's done 67k now so fair enough. I just renewed the alternator few months ago too (I presume that went because of wearing from the old timing belt).Now I'm looking to get these 2 repairs. What do I do?I'm based in South London. Is there a garage someone can recommend? What sort of prices am I looking at? Are these something I can do DIY (limited experience here).Sorry for the long post, want to share my somewhat frustrating experience with you for context!