StashFin — false payment harrasement

Hi, so monthly stashfin debuts rs.7167 from my a/c as it is the emi for the loan i took. The second month i had to pay a late fee but it was not even my fault. They are supposed to take it on 8th of every month and on 7th i received msg that it would be auto debited but due to their system error they could'nt, and then they kept on calling and msging me while i was on work and then i had to go to their website and pay the emi with extra charges. This month they have already taken the money and are still emailing me that they have not received it. The number they have provided never works. This is literally mental harrassment that even when they have already taken the money why am i still getting msg from them. Also, how am i supposed to clear this to them when their contact number never works.
So, please assist me in sorting this out.