Use the advantage of being small
Care means understanding the person and taking useful action.
A small company can give customers attention that a larger organization struggles to provide. You know how much effort the first sale required. You can also see the person behind the transaction. Use that closeness to understand the result the customer needs.
The customer benefits from knowing that a responsible person stands behind the product. A message does not disappear into an anonymous system. Someone understands the situation and acts. That experience can distinguish a young company before its product has every feature.
A pleasant tone helps, but it does not complete the work. The customer needs a result. Listen carefully, explain what you can do, and follow through. Care becomes credible through repeated experience.