Turbo exchange is destroying my life

<p>I recently bought a turbo from Turbo exchange, it came with a 12 month warranty. Less than 6 months after installing it the car started smoking and I took back to the mechanic who did the installation and he stripped the turbo for to take it back to Turbo exchange for testing as it is still under warranty. A gentleman by the name of Mark told me that the turbo is permanently damaged and could not be fixed because it was damaged by contaminated oil. He said contaminated oil is excluded on warranty but when turbo they said the warranty covers everything I must make sure that the mechanic doesn't mishandled it when installing it. The oil was changed with the oilfillter after the installation of the turbo. I haven't been dissapointed with company in ages. Now they are telling me to buy a new turbo from them. What I don't understand is why am I only get to know about this now that oil is an exclusion because mainly turbo's consume oil and how am I suppose to know if the oil if</p> <p>contaminated.</p>