Bad Service

So I got in contact with NDA about removing myself from Debt Review and they sent me an invoice but the invoice send does not correspond with the statements that has been send to me. I send messages to Melanie Smith asking her why does the statement which I sent a screenshot of says paid and the invoice she sent didn't explain anything and she has not responded. I find it frustrating that she firstly didn't answer the question that I have asked and worse off she doesn't even respond to my emails. So my question is what should happen next? I want answers and very urgent please