As a whole it was OK and I'd probly cut out the middle man and book direct to save any confusion

OK Rent a Car is a car rental company that has been around for just one year. The lot is large and the cars are very new. Due to promotional offers for the new company, if you book in advance for a local rental and return it during non-weekend times, you can get this rate. One euro includes several types of full insurance but note that there is a €1000 deductible for damage. You can purchase supplemental full insurance from QEEQ or the car rental company.

The Barcelona airport branch was not great, and they didn't provide me with a paper copy of the rental agreement. The return process at the Madrid airport branch had friendly service, but the wait time for authorization from superiors was very long. They did provide a paper contract and receipt.

The car wasn’t overly clean and had lots of scuffs and marks on. But service was good, and quick.

Lots of hidden fees (gas, early drop off, large deposit, etc) terrible customer service on day of pick up. The service rep made us so angry we wanted to cancel but then were informed we couldn't without talking to the third party booking service. Not in Bilbao airport and very difficult to locate for return. Only positive thing I can say is the car was in good condition. Still waiting for deposit, though it's only been a few days. Wish I would have read more reviews prior to reserving. Won't book with them again.

Query already raised about a fuel tax payment

As above