I think since you were buying the time to make the payment, bank staff thought you were not in the mood to pay anymore. Due to strict policy and because of lot of deafault cases many banks have even stopped leasing, and those facing losses have also become suddenly active.
I remember UBL got a stamp paper signed by me and it reads that I have sold my car to______________ and they can fill any name there anytime they like.
Now the banks are not tolerating any delays. Simple. You are lucky that they did not slap any "repossession" charges on you. One of my friends had to pay 20,000 repossession charges on top of two late and three advance payments. I had been warning him to pay, but despite having money he was in habit of delaying things. Now he doesn't do that.