Is the warranty I bought any good?

Hello. In advance, I thank you for your time and help. I purchased a
Mercedes 2015 GLA, AMG (It's my first nice car,  ever!). It has 55000 miles. 2
owners. I will have the car shipped to me from a dealer. They sold me a
warranty from "Total Warranty Services" for $3,500 for 3 years coverage.
There is a money back 30 day trial.

Are there known issues with 2015 GLA? that warranty may not cover? I know
they can be sneaky and deceptive. The dealer said all engine, transmission
and electronics are covered. In your experience, are the major things that
could go wrong, covered by warranty services? or just the things that never
fail? Also, is 3500 too much for 3 years warranty on a Mercedes?  Again,
thank you. Best wishes for superior sales and fruitfulness to you and yours!!!

respectfully,