Think about what you want, not just what went wrong.
If the terms of the contract are recorded in a written document, it is essential that you obtain a copy of it and provide it to us. Parties are generally free to agree whatever they want, so asking a solicitor questions about whether a contract is legal, without the contract, will rarely enable them to provide you with proper advice.
If the terms of the contract were not written down, write down what you think was agreed, when and between whom.
Gather and place into chronological order any and all relevant documents (including emails) concerning the nature of the claim.