Pimlico Laundrette in London

Returned from Paris today with a big load of washing. Happy to see a local laundrette in Pimlico. Didn't have time to convert EUROs so thought I'd drop off bag then collect and pay when having been to cash machine. No such luck. "It is not our policy", came the unhelpful response. So whilst its a clean and busy place - I didn't find the manager particularly accommodating to my particular needs.