The refund policy is where the guarantee is spelled out. Read it before you pay.
How do I request a refund and by what date? Do opened or finished bottles qualify? Must bottles be returned, and who pays? How are refunds paid and how long do they take? Does the guarantee count from purchase or delivery?
The page does not answer all of these.
Ask by email so the reply is in writing, and save it with your order. If answers are vague, consider a smaller package. A clear policy lowers your risk more than a lower price does.