The last one on Saturday fixed part of the issue then left us with a drain that had holes due to corrosion and said he couldn't fix it.

-You will spend 10-20% more than you and your contractor think you will spend on the remodel  -You will take weeks or even months longer than you and your contractor think you will on the remodel  -If you don't have any design experience, your home will not turn out as attractive as it can be unless you hire a designer or ask the opinion of some real estate agents for finish feedback (think flooring, cabinets, countertops, paint color, etc)  -When you open up walls for any reason, you will almost certainly discover something you didn't know would be there (old plumbing lines, signs of mold, rotted framing, corrosion of sewer connections, unsafe wiring, etc) -Materials will take longer to get to you than you think (due to ongoing supply chain issues).

Invest in assets that leverage inflation.As consumers prioritize their expenditures less towards luxuries and more towards necessities, investments in tangible assets that revolve around consumers' needs and not wants are what will best insulate a portfolio against the corrosive effects of inflation.The ideal asset will generate recession-proof income while appreciating in step with inflation.

Symptoms of aging galvanized pipes were noted, include poor water pressure (choked by internal corrosion), brownish water or rusty flakes in water when first turned on, and leaks (usually beginning with joints).

If its really been there for 12 years there will be tell tale signs like the amount of dust on it, how the vent stack piping looks and if there is any slight corrosion on it or new/fresh screws, newly soldered copper joints, etc.   

The worst possibility is if there are a large number of small pinhole leaks due to corrosion of the pipe.

I would check all the wiring, plumbing, mechanical systems closely for corrosion.

They claim it was due to corrosion.

Aluminum is rather an active metal for such application - might be given to cathodic corrosion issues.

He said there was more corrosion/rot than he realized, and he now needs to replace the sliding door.