Inconsistency

My wife and I have changed our life insurance and sent in our cancellation letters 5 days apart. On 20 January My account is debited for one of the cancelled policies. I disputed it with the bank and it was reversed. When I contacted Altrisk they could not tell me why the debit was done on an obscure date and claimed that due to \re-branding"my cancellations were not received by them. I was then put through to a second person who said that the re-branding had no effect on their email system but they have no record of one of my 2 cancellations. I then sent proof that both cancellation letters were sent to exactly the same email address to which they could not explain why they got one and not the other but I was informed that I would be liable for a full months cover for both my policies in January. I have just received notification that the 1st one I cancelled was effective 1 January. In my book that means that I am not responsible for paying that one. Why can't the same be true for the other??? """