My wife and her three cousins are traveling to Rome in Sept. I have reserved her a Mercedes E class through Avis, for about $2800 for 2 weeks.

One of the cousins has a C class reserved (slightly smaller) but only $2300 WITH the extra insurance. They claim Kemwel is a wholesaler for Europcar.

For those experienced in European rentals, which is more reliable? Which is least likely to play games or "lose" the reservation?

Thanks in advance!