wtf: Pool Tile and plaster people?

My parents have a cement inground pool and upon taking the cover off this year the plaster is badly stained. The waterline tile is also in bad shape in spots and could use replacing. Anybody do this type of work or know somebody that does? They’ve had trouble finding somebody to do it and have only one quote so far.

Colley’s came over and recommended a full replaster and tile and quoted $11000 using some 3m plaster and about $2,000 less for plain plaster.

Acid washing is also an option but the colley’s guy said its not a good one. Also have a quote from leisure craft for $4500 to acid wash and retile.

Not really sure what would be the best option to take but some more estimates would sure help get a better idea.

I will be checking into this soon also,
my indoor pool is missing some tile where it meets the hot tub