Dear Sir or Madam,
I am writing to apologise for returning five books to your library two months after the due date. I know this must have caused inconvenience, as other readers may have been waiting for them.
The books were borrowed in January, just before I had to travel abroad urgently to look after my grandmother, who was seriously ill. I intended to renew them online, but my internet access was unreliable during my stay, and afterwards I simply lost track of time. I realise that this is not an excuse, and I deeply regret it.
I have now returned all the books, and I can confirm that they are in good condition. I understand that a fine will be charged for the late return, and I am happy to pay it in full. I could do so in person at the front desk when I next visit, or I can transfer the money if you tell me the amount and your account details.
Once again, please accept my sincere apologies. I assure you that in future I will return my books on time.
Yours faithfully,
Chen Wei