Retrozone have one of the best records in the community of any shopping site. In addition to great products that carry a warranty! Perhaps you had issues because it was an international order, but that's between you and them.

As for the NES Powerpak, outstanding product! In a class by its own on the NES. The incompatibility list is very small, with I think Castlevania III standing out the most, and that is because of hardware.