False sales

I open a sim contract last year mid december. I was advised that since is the middle of the month they will give me data but not full amount and i will be billed for it. They told me my data will be credited into my account on the 1st of every month going forth. Today i am without data when i call them i was told that my data will be credited on the 12. I asked why they told me that is when my account is billed. I asked why was i not told so when i open the account? They say the must have been a mistake. I told them that i was told that my data will be on the 1st of every month why was i not informed of the information why was i not receive statement since my account was open. Because i vouod have seen that i am billed on the day i don't know of. So i further asked so they were waiting for me to call and ask about my services. This is not my 1st contract with them and this billing of 12 i know nothing about and is not what i sold.