Cash currency conversion conundrum

A problem that affects many businesses both large and small in many different industries is that of working with multiple currencies.

We're currently trying to find a good solution to our own work with multiple currencies; the DJ agency part of our business has a lot of transactions both in and out from promoters, to artists, plus the odd unfortunate refund, etc.
While we have several different currency accounts, the ever-changing exchange rates and different territories we work in are a constant challenge for us. Add to that a few different territories to send client money out to, plus various bank charges and it's a real noodle-scratcher.

I'm still searching for the best solution to this, just for Euros and Pounds, let alone US Dollars. HSBC are apparently 'the world's local bank' but they don't seem very well geared up for this kind of work, particularly 'small' amounts (i.e. under £10,000). Next stop, custom currency exchange providers.

Sometimes I do wish we had the Euro here....