passisng the buck and being clever with me

I am very disappointed with the bank after so many years being their customer, I have 4 contract phones on my account and only yesterday I received a call from a very rude lady telling me that my phone are on collections since I missed 2 payments and they were on settlement in December. I asked why I was only called now and I was not informed prior then she tells me why don't I keep track of my accounts and I even asked her whether she keeps her. she then told me they notified via sms and by post of the areas of which I never received. I even told her sometimes I don't even get their incontact messages for some transaction and she went on with her rude self saying I should went to the branch to fix it. what is very amazing in all this is why were they able to contact me now and they never did all this while with the areas, I have a sim contract and if I skip a payment I do get the sms and the next month they will double debit, so why was it not the same with the phone contracts. I have never got any letter/s and don't remember getting 4 smses telling me each phone is on areas. I am very worried with my future with this bank that only acts when it suits them and benefiting from customers.