Hi, welcome to Just Answer. I will help you with your question.
Yes, there is something you can do.
Obviously, there is no contract in place, so this isn't about breach of contract.
However, where you have a competitor that deliberately lies to all your suppliers/organisers/customers etc., to try and gain a deceitful advantage over you, causing you financial loss, you may be able to rely upon the tort of "causing loss by unlawful means".
You can see a general discussion of this, and related laws, here: http://www.inhouselawyer.co.uk/index.php/litigation-a-dispute-resolution/6929-claims-without-contract-economic-torts-come-of-age
Your principal remedies are likely to be a compensation (damages) claim, together with an injunction, to prevent them from continuing to carry out unlawful practices like this.
The law is quite complex in this area, because it's all based on past cases (no statutes/Act of Parliament).
It might be worth getting a solicitor to write you a letter to these people threatening to get an injunction and to sue for compensation. I expect this might be enough (it usually is, in the vast majority of cases).
I hope this answers your question. If you need further information, just let me know. Please do remember to rate my answer as highly as you can.
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