2016 Nissan Sentra CVT

Hi friends, transmission work was done on my Sentra few weeks ago and I am not happy. It was a great car, no issues until cvt failed at 278000km.

Since the cvt was changed, the car doesn’t feel the same. The car jerk/hiccup once when coming to a stop. It is visible when stopping on a higher speed; it’s lightly visible when stopping on a lower speed. Definitely something is wrong, I told the mechanic it’s a new problem since the transmission work. He says the throttle needs cleaning; I cleaned it and it’s still happening. He says if there are any issues with transmission, the engine light will come on; so he wont do anything about it because there is no engine light.

I was debating to repair; and decided to repair because the was in a really good shape, i maintained it well.

Anyways, I what could cause the jerk/hiccup? Any tips? I feel like the jerk/hiccup could be safety issue when the roads are slippery in winter.

Background Story:
I am in Canada, I made a deal with him to rebuild my transmission as I felt thats the correct way after some researching. It costed me $4200. I dropped off the car and picked it up a week later; he said he couldn’t rebuild my cvt as it’s in a bad shape (i drove to the mechanic in the failing cvt car). He said took a cvt from a 2017 Sentra and rebuild it and put it on my car. i feel like he put used transmission and washed his hands.