Amazon Complaint Of Payment Charges

I am a pensioner and I have been seeing monthly charges of £9.99 from Amazon on my Mastercard ending 7233, even though I do not have an Amazon account and do not know what these payments are for. When I check my statements, I can see that these charges have been taken at least since December last year, roughly seven times so far, and this amount is a significant burden on my limited income. I have tried to contact Amazon about this, but the phone number I found does not work and I have not been able to find a valid email address, so I have not received any explanation or support. I still do not know which service or subscription these payments are related to, and I have never knowingly signed up for any paid Amazon service. I request that any subscription or service linked to my card be immediately cancelled, that no further money be taken from my Mastercard ending 7233, and that all monthly payments of £9.99 taken without my consent be fully refunded. I also ask for written confirmation explaining what these charges were for and confirming that the issue has been resolved.