Do you use a Tesco ClubCard? If you do, that will have a record of your spend. Don't be fobbed off by some lowly customer service rep in store. At a minimum you go for the manager and if no luck there, you email the CEO and complain about the ludicrous 2 hour limit for their patrons.
As already requested, show us the NtK you received. Hopefully when you appealed, you didn't give away the identity of the driver.