Charges Pro Rata without telling the customers what they are letting themself in for

I joined Rain on the first of January and upon joining I thought this company seemed to good to be true, I tried to find out all of the information from the call centre agent who assisted me with the payment for the router but he seemed too busy to be bothered. Today I received my statement and I see that it looks like Rain charges pro rata? Why was I not informed of this? According to the lady I spoke to in the call centre today I accepted the terms and conditions when I app**** for my account, are you not supposed to make your customers aware that when joining there would be pro rata fees so that they can make sure the necessary funds available? Now I am sitting with a failed debit order and debit order fees that went off, and too little money in my account to pay the stupid wifi account. I dont think I am going to keep my account seeing as there is no trust nor transparency between me and Rain