Darlene
We live by our service contracts which explicitly details the services that will be performed. The contract is signed and dated so that we have a legally binding agreement. Hopefully this prevents any mishaps, misunderstandings, etc. Of course, this is literally black and white. No matter what we do there will be one person who isn't completely satisfied. You have to determine if this is worth a full refund or a percentage. Granted if the customer isn't totally satisfied with the work you have performed, you will do everything in you power to make it up to the client and that may means giving back a refund. Of course, the client can view this as positive and give you more business and refer your services to others. This would be a win win situation.
I don't care liablity insurance, but I am looking into it. I do carry Erros and Omissions insurance because I am a notary so I am covered with the notary issues. I never thought about having Errors and Omissions for the VA business.
Good Luck in making your decision.