Have a deposit on a 2017 GLC 300 but in recall ****!

Help! I searched hard for a Used GLC 300 with the AMG sports package, illuminated star, navigation, parking assist, etc and finally found one that I LOVE! I put a deposit on it and have been waiting and waiting for the dealership to get the part to address the recall for the steering ring that has the car grounded and will not allow the dealership to complete the deal! UGH This car has it all! It is listed at 42,900.
The wonderful salesman I am dealing with told us he was getting a few 2018's with the AMG package and we could compare those when they get in and he will discount it well.
So they came in last week and we took a look. One white with the night package, illuminated star etc...and a couple of gray with different packages. The biggest difference is the used one has upgraded paint Diamond white, navigation, parking assist, ambient interior lighting and real saddle brown leather with black accents. Its sexy!
The new white one that I am seriously considering is all black leatherette with ash black wood accents, which I do not love, smartphone integration that I wanted and cannot get on the used one, night package which looks sharp and the used one does not have, but apples to apples I like the used one better.
Problem is I desperately need a car! I am sharing my husbands with him and he travels!
Mercedes USA cannot tell me when the part will be available for the recall and I cannot wait another month just for them to say it may be another month after that...I am scheduled to buy the new car tomorrow, but I am second guessing myself. Can I take this used GLC to a mechanic and get it checked out and buy it un-certified?
What would you do?
Thanks for any advice!!!