As far as I am aware, 25k is the maximum unsecured loan you will get in one go.
In theory you could approach more than one institution but you would either have to tell the second one that you already had a 25k loan elsewhere (which would probably influence their decision) or you would have to attempt to deceive them (not wise!)
Maybe if you had some kind of private banking in place you could negotiate more, but then as a 21 year old I suspect this is not the case for you?