Sounds like a load of old Tosh to me ! Typical UK bank. A bigger bunch of incompetents, thieves and sharks does not exist. I don't miss them at all. Maintain 600 Euros ? I'd tell them to take a hike. Cheapest, as in saving on transfers, may not always be the best.
We bank with Bancaja (I have no connection with them whatsoever) and they have been very good.
Direct debits you want stopped because you don't agree with the amount ? Phone the bank and it's stopped. Wife left her card in the cash till ? The machine swallows it back to prevent theft and then texts her that they have got it. In English..... Need a new PIN - walk into the main branch and they will print you a new one, there & then. Internet banking is a breeze. Draw some cash and it will show within minutes online. None of that 3 day clearing nonsense in the UK
We use Moneycorp (again, no connection at all) to change from Sterling to Euros. We have an account so pay a flat fee. They may not be the cheapest but they have served us well, and every month for the last two years, the money has come from our UK account to our Spanish account within a few hours. yes, it CAN take up to 3 days for a transfer abroad, but we've never experienced that yet.
It's difficult to compare some of the companies as they agree a buy / sell rate on the spot which may change later. So if I get a quote from one company I may get a different one from another one, not because they are more or less expensive but purely becuase the rate has moved.
We leave a small sum of Sterling in the UK for when and if we need to go back and bring the rest over.
So I'd go with a Spanish bank. Like many things over here, in some ways they are light years ahead of the UK.
And it just goes to prove - look after your customers and they say nice things about you !
Good luck