You are the merchant, so the decision is entirely yours — Friday Scheduling never held the payment and cannot return it for you. That also means you are free to be generous without asking anybody, which is the part worth using.
Offer the fix before the money. Most unhappy clients want the result they came for, not their money back, and a redo booked in the next few days costs you an hour rather than the whole fee. Say what you can do, when, and at what cost to them, which is usually nothing.
Where a redo is not wanted or not possible, decide fast. A refund given in an hour buys goodwill; the same refund given after a week of argument buys nothing, and by then it is often a chargeback anyway. Put the decision in the message thread so both of you have it in writing.
Not everything warrants one. A result that matches what was agreed, a client who changed their mind about a colour they chose, damage from something done at home afterwards — those are conversations, not refunds. Say no clearly and offer what you can instead.
Then write it down. A short note on the client's record explaining what went wrong and what was agreed is what stops the same conversation happening twice, and what tells you whether a pattern is forming with a particular service.