Unfortunately, there were several screw ups, with several buyers participating in the program receiving a smaller credit than originally quoted. One person trading in a Pixel XL, expecting a $400 credit, was told that he sent in a Huawei built Nexus 6P and had the original $400 credit sliced to $165. Others sent in phones in absolutely perfect working condition, only to receive correspondence that suggests otherwise. Others had the amount of their trade-in reduced because they sent in the device with a case on, or failed to disable factory reset protection.
Yesterday, Google posted a message in the Pixel Phone Help site that says it has “identified and fixed the issue related to Pixels not being found to be factory reset and/or misclassified as another device.” If you have had problems with the trade-in program and aren’t receiving the amount of credit that you were originally quoted, contact Google Customer Support right away.
Source of news : Phonearena