naturalization application will be refused help

[himya]

naturalization application sent on 18 of January.
received acknowledgement letter after 4 weeks on my address that i have written on the application form.
on 25 of April i received a called for my previous landlord( who i moved from his house 1 year ago) that he has a letter belongs to me.
it was a letter from naturalization department with my passport with it.
the letter stated that i sent the wrong English Language test(was Ielts C1 was my fault found out later ) i have to send that GCSE 5 B1.And i have to submit this document by 13 of April otherwise my application will be refused.
they send the letter to the wrong address i never mentioned that i m living there even the acknowledgement they sent to my current address.
i have written to them saying what happened
please tell me what i could do in case they refuse my application because i did not submit the document on 13 of April it is already 2 weeks over
thank you