ESA with IR restriction

I have today found out that the DWP have put a restriction on the top up of IR ESA. I have been on ESA support contribution based for some years.
March of last year they asked me to provide bank statements and a completion statement of a house move that happened in 2016!! even though i sent them everything they needed at the time.
I had the completion letter but had to approach the bank about the bank statements as there were 60 odd pages. I called the DWP and told them i would have to apply to the bank for the statements but it shouldn't go over the send by date on the letter. Sadly Natwest on three occasions sent the wrong bank statements, so much so they were so embarrassed by their error, they sent me flowers. I called the DWP and told them of the error and that now it would go over the send by date,which they noted.

Finally sent everything off and didn't hear any more from the DWP, meaning i was on contribution anyway so capital didn't matter.
I recently had a benefit check done and they stated i should be entitled to a IR top up, as i have no savings and low income. I called the DWP only to find out that ive had a restriction put on my benefit because I didn't send back the info requested back in March 2018 by the date it was due.. I didn't receive anything back in 2018 telling me about the restriction... what can i do?

Thanks Gordan, im waiting for someone to call me with a VERBAL decision, so i was told... I didn't receive the letter or any other paperwork they are talking about... So in theory since March 2018, i should have had IR top up.... she asked me why i'd left it a year to contact them, because i had assumed i was just on contribution based, i didn't understand the benefit process.