Have been registered with bank now can't get shift...

Have been registered with bank now can't get shifts as they need sonsome to start sooner. When I did inform them during registration that once accepted I will have to give 4 weeks notice at my current job now they are saying none of the Pharmacy managers are willing to wait that long. I have sent them 2 emails did not receive any reply, phoned them said someone will call me back no one has & now to be told this is ridiculous. I will be jobless after 2 weeks. I don't know what I will do. they say they can't do anything for me.