Welcome Selvam to TAI
there are some questions appropriately raised by "Bumpy Ride" and "Dodge" and I would like to ask some more. Please note that a hole can be covered by mud/rust easily and definitely can get uncovered by the cleaning. Now to the questions
1. How old is the car? It is rare for a car muffler to develop a hole if the car is within 3 years of age.
2. If there is a hole in the muffler due to corrosion it will have many lips (hole circumference will not be uniform), if made by a person using a punch the surrounding area will be depressed slightly than the rest of the muffler. The hole also will be quite uniform. How did the hole appear to be?
(In any case a hole in the muffler means that you need to take a piece of steel plate (cut from any old steel box) and stick with a resin/hardener type of sticking medium like M seal, Cordobond, Araldite etc. on the hole.)
3. Difficult to decide about the missing steering oil but please ask the mechanic/service center which repaired it whether there was any seal leak , damaged seal due to which this may have happened etc.
4. Please let us know the Name of the Service center.