Pathetic service with sim swap and billing

I have been billed in advance for My services but now I am told I am billed 2 months after using the service which is bull****. I have done a sim swap with you guys on the 15th which till this day I didn't receive a new sim card yet u guys want me to pay a full month usage. I have called in twice this morning with no assistance. I have been going to work at the government libraries because I have not been able to work due to no sim card delivery. My name is Espe Amisi