It's 20% off the rental charge only. It doesn't include the excess waiver or any other extra options you select. So for example a £25 rental + £20 excess waiver = £45. Minus your 20% rental discount is £5 so total you pay becomes £40.
20% off of £45 isn't £5!
If you didn't get 20% off your rental fee then just tell whoever you speak with at the collection desk. I'm sure they'll adjust it for you. I've used this code a couple of times now with no problems. Always 20% off.
No, it's always 20% off your basic total. How much that works out to be just depends on how long you're hiring and what vehicle you select.
Discount must vary. Gave me £5 off.