Wrong - by waiving the surcharge the retailer has offered to complete the original contract so you have no entitlement to a refund of deposit (unless you explicitily agreed that the deposit was refundable when you paid it).He then said he would waive the visa surcharge. I insisted that I was withdrawing from the deal, as was my legal right.
The retailer was in the wrong not to flag the "surcharge" originally. The card schemes don't like surcharges and try to forbid them in the merchant agreements but in practice merchants seem to get away with applying them via other means (separate card processing fees, cash discounts, etc.).