Car hire in Europe with the AMEX Paltinum Charge card and MP Diamond

[gvix]

I am trying to figure out the best way (economically) to hire a car in Europe with AMEX Platinum Charge card and the Marco Polo Diamond memberships.

BTW, I have complimentary Hertz. No 1. Gold with AMEX Platinum, bit sure if it helps.

I need to hire two car seats as I will be travelling with kids.

At the moment, Hertz gives me the following rate. I am using Marco Polo rate and have therefore only got the rate for the most basic car as I should be given a two car upgrade.

I am renting in Spain for 9 days in Sept.

1 week at 38.30 EUR	38.30 EUR
2 extra days at 5.47 EUR	10.94 EUR

Rate Details

	VEH LIC COST RECVRY	Included
	Drop fee (Paid At Counter)	45.00 EUR
	Estimated mileage	0.00 EUR
	Collision damage waiver	81.09 EUR
	Theft protection	13.50 EUR
	Taxes	33.99 EUR

Vehicle Subtotal

222.82 EUR

Extras

Booster Seat (x1) ​	70.80 EUR
Child Seat (x1) ​	70.80 EUR

Extras Subtotal

141.60 EUR

Total Approximate Charge

364.42 EUR

My questions are:
1. Can I refuse the CDW and Theft protection and pay with my AMEX Platinum at the counter? AMEX Platinum covers me for these.
2. I am getting bummed with the car seat hire. I will need to rent a car again in 10 days after this, and will need to pay that again. Is there a way to get past this? Is there any program or promotion that helps to give free baby car seat hire?
3. Any way to reduce this even further?

Thanks!