Three weeks ago I had my oil changed at CT ... Last week I was driving along and my car just stalled ... the mechanic told me my engine block is [seized] ... due to lack of lubrication. ... this CT has done all the sevice on this vehicle.
I have not had your exact situation but something similar with a mechanic.
Are you a member of CAA? They have a “technical questions” line where you speak to someone about repair problems, and get some informed and independent advice.
In my case, the rear bearings were incorrectly installed, and quickly burned out. The mechanical claimed that it was my fault because if something went wrong, I should have noticed. Or, that I must have done something afterwards that caused the problem.
The advisor at CAA, as I recall, said that it was the mechanic’s responsibility to perform the work correctly, and it was not my responsibility to make sure they’d done the job right, and there was no proof that I had somehow damaged the bearings. I just drove it normally. And, had there been any issues with the car that would have affected its use, it was up to the mechanic to tell me.
But, get some good advice for yourself - do not go just by what I say. I'm just an anonymous person on the internet.
I wonder if you maybe should get another mechanic to verify that there wasn't a problem after CT serviced the car, such as a hole in the oil pan.
Something to think about: if CT offers to cover the labour if you pay for the parts, you might not want to go along with that. Remember, they weren’t able to change the oil, let alone replace an entire engine.
I've sure some CT stores have good mechanics, but there are so many stories like this one, that in my opinion nobody should ever trust CT with their vehicle.
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Also, please ignore the strange behaviour of the Unregistered "LOL" poster. I suspect they are just trying to interfere with anyone who tries to help (ex) CT customers.
P.S.: It's "seized".
Good luck!