How to manage customer expectations in fixed quotation items

Our company is doing offshore software outsourcing. Although most projects are working with customers in the form of ODC, there are also many fixed-price projects. We obviously feel that it is difficult to achieve a good customer satisfaction in a fixed quotation item. In many cases, our developers have paid a lot of extra work, but cannot get the customer's satisfaction. This issue undoubtedly has a negative impact on the cooperation between the two parties. Is there any way to deal with it? I spoke to a friend about this problem today and shared some experiences with you.

First, we think the entire team should have a correct understanding.

• The customer's expectations can be adjusted, not static;
• The more customers understand the actual situation, the more helpful they are to establish reasonable expectations;
• Changes in the environment or the actual situation are important reasons for the expected adjustments;

Then, based on these understandings, the implementation of the following policies will help to manage the customer's expectations-

• Before starting a task, try to clarify the project scope, time, resources, and other constraints; eliminate wishful thinking assumptions;

• After the two parties reach an agreement on the above factors, it is best to turn them around; try not to leave anything that may lead to wrangling;

• In the project implementation process, we must strictly monitor the changes required to prevent the spread of scope; Do not think that some small changes do not matter and accept them directly. Too many small extensions will eventually flow into a river, as a result, changes must be centrally managed and controlled regardless of their size;

• If the scope needs to change, it is necessary to communicate with the customer in a timely manner, clarify the impact of the change on the progress, quality, and cost, and adjust the customer's expectations;

• Determine in advance the possible impact of the planned scope, time, and resources. Do not rashly Commit Changes or accept new tasks from the customer;

Although this does not seem agile, these methods only target contracts such as fixed quotations. Customers of other types of contracts may expect different management practices. Any better idea?