What is the budget? How much did your repair cost them? In my area most panel change outs would cost less than $1500.
I have on many occasions had to replace the guts of Zinsco panels. I do this when the panel is a small meter/main combo flush mounted in stucco on exterior walls.
Zinsco panels are notorious for pitted bus bars, and that pitting is what causes the flickering and tripping of breakers.
Zinsco panels are small, and most of the time they are full, but I have on occasions found a pitted bus bar on one breaker, and simply bought a new breaker and placed it in a spare slot.
I buy the replacement bus bars from an "electrical junkie", he has a warehouse full of old and new electrical parts. He has been accumulating his inventory for decades, and was a former electrical contractor himself, he really knows electrical.
His name is Kurt Allemand and his shop is in Ronhert Park CA.
Kurt told me that if a person exercises the Zinsco breakers only once per year, that it will help prevent the pitting, he said that every time the breaker is opened and closed, it actually makes contact in a slightly different location on the bus.
But, since Zinsco breakers are also slow or no blow, when people overload them is when the pitting happens.
I did not know that replacing the bus and breakers would de-rate the panel, but Zinsco breakers and panels with their aluminum bus bars should have been de-rated as soon as they were installed.
Personally, I would rather spend $225 on a bus bar than replace the whole panel for my customers. Often times to replace the whole meter/main combo would cost well over $3,000 considering all the work and permit costs, and getting a business license in that city.
I guess it depends on how much work one is wanting to do to fix the problem, but , I only work for long time customers and I will do my best to save them money and myself work, especially in a critical emergency situation.