Support for defective goods should ultimately be the responsibility of the manufacturer and not the seller. This is a basic point of consumer law in many countries.
Yes, depending on agreements between the seller and Doogee initial contact should be made to the seller. although I doubt if Doogee has made any such agreements, like for example, Samsung generally does.. If the seller is not responding then the manufacturer should take some responsibility and stop providing the sellers and or distributers.
As it is, Doogee are just palming off any responsibility and AGAIN, totally ignoring customers. Simply by not responding to posts such as these, it clearly shows that Doogee have no duty of care.
Just a bit of advice for some users who have purchased using a credit card: Many credits card providers do provide by default a basic insurance whereby you can claim back from for defective goods.