English B1: A complaint

You ordered a backpack online, but it arrived broken. Write an email to customer service.

Dear Sir or Madam, On 3 May I ordered a blue hiking backpack from your shop (order number 48213). The parcel arrived yesterday, but unfortunately the zip is broken and there is a hole in the side. I need the backpack urgently because I am going on holiday in two weeks. I would therefore be grateful if you could send me a new one as soon as possible. If that is not possible, I would like a full refund. Could you please tell me how I should send the broken backpack back? Thank you in advance. Yours faithfully, Laura Baker