This works at at pay at pump. Including shell/texaco/tesco/morrissons/asda/esso etc. Your debit card must have £1.01 available on it. You must use the pay at pump and not over the counter payment. You can avoid bank charges with this as it will get you out of tight spots. Usual fuel limit is £100. This should also work with credit cards as well. It can be used to your advantage. Debits can vary from 2 days up to 7 days. You need to time the use correctly so if you are out of money the debit for the fuel hits your account on a week end. This way although you will be overdrawn you will not be hit with charges as the overdrawn day will show as the next working day. In which case you can pay money into cover it without being hit with charges. Its trial and error.