Hi, my name is Curly82! I've been waiting to hear back about a backdated payment for SDP

I am getting severe disability premium but I have been waiting for a call back about my backdated payment, I do not get any callbacks, my severe disability is awarded from January but I was told I would get a decision about how much backdated I would get by the end of February, then I was told they would pay me while I wait for the back payment they started paying me but if I call to talk about the back payment they never call back, I have not got a voice, the people on the phone say there is nothing on the system, but I was originally told that I would get a back payment from 2013 do you know roughly how long that would normally take and should they be calling me back, I have made a few calls but no one ever calls back,