Payment for FSHC

My Father in Law past away on the 14th November 2017. I went to FSHC to inform them and that We are taking my Mother in Law out of the flats were they told me that We must pay a month extra because we did not give them a month notice. We paid it on the 16th November 2017. They said that are paid up till the 19th December 2017. The inspection was done on the 17th November where my Mother in law give them the prove that we paid that. 1 month notice. Now we get freds from FSHC they whant to take us to the lawyers and that we own then now 2 months. They did receive the month notice and they still have the deposit as well.