All of our car rentals in Europe have been through Auto Europe or Kemwel since 2011. We had two rentals for this summer, one for Croatia in June, and one for the UK in August. Looks like you can no longer cancel via their website unless you accept a voucher with +10% added.
But had no issues cancelling both reservations via the 800#. (And was in hold for less than 5 minutes). They did suggest a voucher, good for 3 years plus 10%), but once we return to the US this year, have no idea at what point in the future we will return to Europe.
AutoEurope, in the midst of this crisis continues to offer great customer service.