This varies from bank-to-bank and by country.
From a UK account this usually takes 4hrs, and can take up to 1 working day. BACS payments take 3 working days.
International transfers (from Poland, Switzerland and elsewhere) usually take 1-3 working days.
Transfers from Greece typically take up to 4 working days.
If you are topping up your account with USD, PLN, CHF, SEK, NOK, DKK, RON, AUD, NZD, SGD, HKD, ILS, TRY, AED, CAD, HUF, INR, JPY, MAD, MXN, QAR, THB or ZAR please ensure you use your 8-digit customer reference number as the reference/description for your transfer, or we will have to manually allocate your top up. This will delay the top-up reaching you account.