The loss that you have potentially suffered here is called consequential loss or sometimes pure economic loss. It can be recoverable provided the loss is “within the contemplation of the parties”.
What that means is that if you told DHL that it was imperative this parcel got to a particular place by a particular date otherwise you would suffer huge losses, then it is recoverable.
However if you did not tell them that, then they couldn’t have known about the potential loss and it is not recoverable.
Even if it is recoverable because they were aware of the potential problem, there is another problem and that is that even if you had told them how important this was and it was still not delivered on time, you are going to have to prove what you have lost. That is not going to be easy and you are certainly going to need advice from a forensic accountant. It is almost impossible to quantify how much this PR opportunity is worth and therefore that is extremely problematical. It is valuing the claim which would be virtually impossible
This is a guaranteed service then it would appear that they are in breach of contract and in breach of the provision of the Supply of Goods and Services Act for failing to carry out the contracted job with reasonable care and skill and within the contracted timescale.
I’m sorry this is bad news for you.
Can I clarify anything for you?