Food Truck Nightmare

Location: Kansas- trying not to run on the story but it is a bit extensive

I had purchased a food truck and had an install by the same person. Whole unit is on a lease so I do pay a lease, insurance, and all inspections are complete. Note this whole process had started early this year. March or April if I only recall in my head.

In a turn of events here is a breakdown

Vehicle purchased and truck built- inspected and ready in about 2-3 months

Drove back and had issues with < 100 miles after 2-3 food truck events

Towed to mechanic referred by builder to fix in town 3 hours away- found more issues digging further and had to rebuild. Agreed to fix with parts costs only.

Towed back to the builders shop and tested fluids by local mechanic and ran for checking for issues after vehicle was considered fixed

At local shop catalytic converter was stolen in lot. Mechanic agreed to take to local shop to fix after repair

After inspections I drove the truck about 45 minutes home and towed to local shop after knocking showed up under hood, fix was to rethread pulley bolt. Mechanic said it was inaccessible and had to removed fan shroud to be able to rethread. Fixed

Shop drove vehicle to another shop to fix catalytic converter. During drive white smoke came out and after inspection technician found coolant intrusion in the engine oil. Nobody is taking the blame here.

What i ask is

Who should be responsible and/or what are the next steps for me to take here