Bag packaging with poor service

I ordered a lunch bag that for that which I start on the 4th. I ordered before and I received the order before hand as soon as I got it I found that the shoulder strap was missing so I logged a return and explained to them that I need the return before the 4th. The now booked a return for the 5th. I called the called center and the guy I spoke too said that they will try to accommodate me. How can there be an accommodation for something I paid for and needed for a day that I go back to work. I did not do any damages it was while it was getting packed that they missed out the strap. How do I carry my lunch in an corporate environment. Should I use a checkers packet? The agent was suppose to get back to me after escalation but got nothing back. I am truly disappointed with the service.