Kids trust their parents to protect them and keep them safe. But violate that trust just once and you'll have a kid with a lifetime full of pessimism about people.
Customers aren't that much different. They want to know how you'll help them and protect their money no matter the environment or circumstance.
If you want a good way to lose your most valued customers, be unpredictable. Don't give them what they want. Give them what you think is better, constantly. Give them new terms, new policies, new ways of contacting you, new promotion cycles, new branding mandates...and take away the old stuff just because it is old. Better yet, don't tell them what you're doing until you've done it. Surprise! We're better than ever!
In this world of unpredictability, trust is everything. Once you have trust, make sure you keep it. Even if it is boring.