Bike: 10 year old Norco Indie 2

Took my bike in for a full service a month ago.

Took it on my first ride, started up an overpass, shifted to lowest gear of 27, and the rear wheel locked up. Derailleur dropped inward, spokes stuck in idler pulley, hanger bent.

Took it back to the shop, they charged half to fix it.

Rode about 100km over the past month, and same spot, just started up the overpass, second lowest gear (shop told me lowest gear can have issues), derailleur dropped inward, spokes on pulley, bent hanger.

Shop merchanic immediately said the limiter is set wrong, but they've set it the last two times. I'm assuming they would set it correctly...

Is it something I'm doing?? Is the shop fucking up? Is my derailleur itself fucked and not holding the limits they set?

I want to know what's going wrong, because cabs are expensive, especially during COVID, when the shop can't get my bike back to me for 2 weeks.

Any help is appreciated. Thank you.