1.Causative structure: "because they perceive an increase in the value" uses a causative structure to explain the reason behind customers' attraction to free gifts, adding depth to the explanation.
2.Present participle as an adjective: "Receiving something extra at no additional cost" uses the present participle "receiving" as an adjective to describe the action, enhancing the complexity of the sentence.
3.Noun phrase as subject: "This sense of added value and the thrill of getting a bonus" serves as the subject of the sentence, using a complex noun phrase to describe the feeling, showcasing advanced grammar skills.