How to buy PX4 GPS and compass sensor

Dear All,

I have a PX4 flight controller which is already working but it cant properly controlled, Few month back I chatted with a agent and they tolled me buy a original GPS and compass that will solve the problem. So unfortunately I can’t remember the person I chatted with. So it would be appropriated if you can give me a location to buy PX4 original GPS and compass module

Thanks in advance