Software developers should be prepared for direct customer calls. Acquiring a new customer can be five to 25 times more expensive than retaining an existing one. Successful customer calls require preparation, planning, focus during the call, and follow up afterwards. The customer is demanding (and rightfully so!). They expect (and deserve) good and quick solutions to whatever issue they re facing. It may not always be nice to hear, and you might get criticism, but it is real. It means the customer is using your product and wants it to work they haven t given up on you.
Source: https://www.imperva.com/blog/when-the-going-gets-tough-rd-calls-with-customers-doing-it-right/