When will my unconditonal offer show as unconditional on ucas?

I have an unconditional offer from birmingham, which I have firmly accepted, but I'm getting a little worried now because ucas still says it's a conditional offer. It says in the details of the offer that if I firmly accept the offer it will automatically be changed from conditional to unconditional, but it's been around 2 weeks now and it hasn't changed. How long does it usually take them to change it on ucas?