"I had no way of getting my money back"

I visited my sister-in-law at this hospital. The ticketing system wasn't taking cards so you'd think that being a Sunday they'd leave the barriers open.Anyways,I parked in D and went about my visit.On returning I offered their machine a £20 note all I had on me,to pay for £2.60 fee.I got £10.30 change in coins.You would have thought that a bit of common sense would tell them to put more change in those things as there was no attendant but nope. Being a Sunday evening I had no way of getting the rest of my money back. The man who responded to the call at the machine had no idea, there's no number or email address to contact anyone, I live over 100 miles away and at their front reception desk is a sign that says they don't deal with parking queries. What a nice arrangement. Driving more than 200 miles to claim £6.30 doesn't exactly make economical sense, does it?