Plat farming is done with VPNs, or by reseting the device. What happens, is that NativeX will not recognize your device, and think you're using it from another device. Usually the offer disappear when you receive the platinums.

If you can still see the offers after you've done them, it's a problem. Since you're using the same device, the problem would be more like bug abuse, which you're not willing to do. Usual email: supports at spacetime blablabla