I am a preferred member and I have noticed that my rentals are not being booked on my preferred membership

I am a preferred member and I have noticed that my rentals are not being booked on my preferred membership. Avis states I have only rented twice from them, amounting to €1569,84. I could find four rentals from my statements, amounting to €3573,02. Thats double the amount of rentals and more than double the amount they say I have paid for rentals. This is very dubious practice from Avis. I would love to hear their response.