My advice is to get in contact with your nearest local GSM service, I'm referring to any type of GSM service, not an official Xiaomi service, but have to be a service which do phone repairs and not only put screen protectors and sell cases. That because in many cases spare parts cannot be easily find by a regular person.
You can try A|i-Express, but it is hard to get this type of particular component. I tried before writing this message but without any luck. Maybe it is a compatible with other models, bust it is very tricky to unsolder it and solder it back, because it is placed on the main PCB.