It's been a couple of years since we were there last Toffeman but there has always been a change booth at the bottom of the main street on the right hand corner if coming down . (beach end). We always got a good enough rate from him although others may know of better if you want to cash a large amount .
Just returned from Olu Deniz yesterday and changed all of my money whilst there. all of the tour shops exchange money but we used Activities Unlimited. The exchange rate at all of them was better than here, we got 227 TL to the £
I saw lots of people changing money at our hotel reception which was just as competitive as out and about- not sure about the rate at your hotel though Toffeemen.