Having worked in this area, both as a client and as a consultant, customer understanding is a key to differentiating yourself from your competition.
First a personal belief: surveys are the worst tool to uncover any insights. They are best used to quantify how many do X.
There are a couple of ways we look for insights into customer behavior, and they are both related by fact that you learn by observation.
First is to have your customer demonstrate how they use your product/service, or the product you want to replace, in their normal situation. Ideally you let them run through once just observing what they are doing while taking notes. Then ask them to go through it again where you ask them open-ended questions as they go along. No judgement, just watch and learn.
The second way is to engage them in a serious game, something like the ones we use from Conteneo.co. These are frameworks designed to have the customer create things like the Product Box which encapsulates the key features, benefits, etc. that they are looking for in an ideal product/service like your.
The reason these techniques work well is that the customer is comfortable, they are not being interrogated, and you are cast in the role of the observer, so you're not selling!
Let us know if there's something we can do to help you with this, because it's an important question.