2015 Subaru XV Crosstrek transmission

I need help! In January I had a transmission fluid change done at Valvoline. Previously no issue, just regular maintenance. Afterward there was a burning smell so I took it back and they redid it for free. There is still a smell when going up an incline for work and i’m not sure what the issue is. they insist everything was done properly and that there shouldn’t be anything wrong. Does anyone have an idea? i’m being quoted $500-$800 to redo it and can’t afford that.