Someone else paying my account

I have had a tablet since Apr 2016 and have been paying it myself since then. This month I noticed that my debit order did not go off but my statement shows paid. When enquiring about this I was told that my banking details was changed to that of a Trust ( which I am not a trustee or beneficiary of). I indicated that it is not my bank account and that the should refund the trust for paying for my account only to be told that will be impossible because I requested the payment to be moved! Firstly I did not request my tablet to not be paid by me and secondly how on earth can I just request someone else to pay my bills!?