For the Basic plan there is a charge for each support instance. A support instance is:
When you contact support you will be required to provide a payment method before working with a support technician. You will be billed once the issue is resolved. Consult the pricing table above for the per-instance support rate for your plan.
Some issues are not billable, such as:
If you are self-hosted then issues connecting to your data ARE billable. This includes assistance transferring from hosting to a self-hosted instance.
Yes, under the same per-instance rate and rules as the Basic plan.