This is not a problem at all - when credited to your Melbet account, there will simply be an automatic conversion of one currency to another. It is easy to assume that the British have all accounts in national fiat currency, that is, in pounds sterling, but the bookmaker does not allow creating a gaming account in them. If you have already created a gaming account in dollars, euros, or cryptocurrency, replenish it without thinking about currencies - the replenishment will still pass!