1, that film is not impossible to tear, so if what you said is true, then the shop assistant's statement is incorrect. Just go to Huawei's designated after-sales point. They can find out the relevant information of your mobile phone and show Huawei's network access license.
2. Huawei is a domestic product, and there are no parallel imports (where do domestic machines come from? Foreign mobile phones enter the domestic market through informal channels, which is called parallel imports. Moreover, the overseas price of Huawei's same mobile phone is generally higher than that of China, because there is no situation in which foreign mobile phones are bought at high prices in China and then sold at low prices.
3. With regard to the requirement of return and exchange, the quality of mobile phones sold in physical stores is not good (Huawei is required to show the test instructions after sale), so you can't return them at will unless the consumer negotiates with the physical store, but it doesn't mean that the physical store is obliged to return the mobile phones without quality problems.
4. If you buy a mobile phone in Huawei Mall, Tmall Mall (not Taobao) or JD.COM Mall, there is no reason to return it within 7 days, which is legally based. 7-day unreasonable return must ensure that the appearance of the mobile phone is not damaged, and the documents and packaging boxes are complete.