I dispute with my friends

How difficult can it be to send me the mail box key for my new apartment? I wasn't given it when I moved in, so I phoned the estate agent up about it. They promised me that the landlord would drop it in to the office the next day. Five weeks later and I am still waiting for it to arrive. I phone them twice every day at considerable cost to myself (mobile roaming costs are extortionate). What else can I do? If I were in Cardiff I'd be sitting on the floor of their office with a book, refusing to move.. until they sorted it out.