The terms of service includes a bit that says:
Orders are not eligible to be cancelled based on the quality of service/materials delivered by the Seller if the service was rendered as described in the Gig Page. Buyers may rate their experience with the Seller on the Order Page, including the overall level of service quality received.
Maybe you could ask for a guarantee of a certain amount of accuracy?
What was the gig for? Manual data entry or something like that?
You could ask for revisions if you notice errors/inaccuracies.
is there a limit to the refunds available?
Fiverr probably does keep track of the number of refunds / cancellations give so there probably is some limit but that isn’t shown anywhere I think. The seller can’t refund/cancel after an order is set to complete as far as I know. Customer support probably can if it’s within a certain amount of days (such as 14) since completion, maybe if they agree you didn’t get what you paid for.
Normally it’s probably better to ask for revisions if something isn’t all correct with the first delivery.