Suzanne, it's not about ferocity or intimidation
It's about "authority" and honoring a promise
You would be entitled to claim for the cost of ALL the parts he said you could have (at secondhand prices) plus all "out of pocket" expenses like phone calls and fuel costs for personal visits
Tell him you'll be sending him a bill for your expenses and compensation for parts not supplied as per the original agreement
I think daily phone calls will get him motivated just to keep you quiet
( try using someone else's phone too, in case he has caller display or blocks your number
)
I do hope you get an early resolution