When I started working at Automattic I did 3 weeks of support. One thing that struck me was our refund policy. Basically, whatever the reason, if the client wanted a refund and the credit card processor would let us do it, we would refund. No trying to convince them otherwise (we did try to fix any problems they may of had first, if any), no trying to sell them on another plan etc.
I’ve noticed that when a place offers easy refunds, I’m much more likely to buy things I’m not sure about. Two of those places that come to mind are Amazon and Home Depot. Home Depot is so great with refunds that my default is to buy more and return if I have too many. Now of course, sometimes I don’t return them and Home Depot made more money. Also they’ve become my default store for anything home renovations. Same goes with Amazon. It’s so easy and hassle free to return something that I’m much more willing to take a chance on an item I’m not sure of.
All that to say, if you treat customers right when something went wrong, it’ll probably pay off in the end.