EcoFlow Bi-facial solar panels not compatable with 3rd party MPPT chanrgers

Bought a bi-facial solar panel from them, I noticed the power drops to 0 every 10 minutes, for 30 seconds. Logged a return. Turns out their solar panels are not compatible with 3rd party MPPT controllers. Now they want to send me the same one back. Been 3 weeks now, I want a refund. They only reply to their support mail once a week. Don't ever buy anything from them.