A few months ago I had a similar experience, noticed one of my rear tyres was very low on air, drove to Shell garage just up the road from work. No cash for airline. Garage had cash machine outside - out of order. Went into shop to see if I could get some cash off my card. Attendant wouldn't do it. Offered to buy something or fill up with petrol to get cashback, attendant refused. Explained my tyre was dangerously low pressure, still refused - not policy to give cashback.
Had to drive home and sort it out there (yes I suppose I could have put the spare on but it was filthy weather).
Meant to write snotty letter to Shell but of course never did.....