Submitting EPS's late - can't do it please help!

I have 6 EPS's to submit to for SMP that are overdue (yes, I completely messed this up - I am a complete rookie). I can't submit them, they just get rejected. It suggested that my government gateway details may be wrong, have checked these and they are correct. I imagine it's because the EPS's were meant to be submitted each month between the 6th and 19th. But what do I do now? Would appreciate some help so much!