I'd be tempted to keep the plastic pond, glue on a bit of plastic from the water side, and then use a liner.
You could use glass fibre but if it leaks again you are back to square one
Depends where they are, if theres a decent volume of water below the repaired holes it may be worth taking the chance of a repair holding. If not, theres nothing worse than getting a pond populated with plants, fish or wildlife and loosing it all if the leak springs again.
Looks like the OP can't be bothered to come back with anymore information.
I can't see the point in asking a question on a forum with many different types of experts and not adding more information. I have being a Koi keeper for many years.
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