PEP STORES- CAPFIN NONSENSE

I have a loan from Capfin, I get paid on the 27th of every month. When applying for the loan, I requested that they debit my account on the 27th and they said no the only available date is the 26th. This means every month they try to debit my account and it fails, on the 27th they manage to get the funds. It is a one year loan and for the past 7 months I have not missed a payment. Now they are sending me messages to say that December installment will be debited after the 07th of December or after the 14th if I get paid after the 07th. My salary date has not changed, my loan agreement has not change. What nonsense is this that I am receiving. This is unacceptable and not professional at all. I don't have anything on my loan agreement that says payment date can be changed as they please.