If a contract has been signed, or there is an oral agreement on WeChat, it can also be notarized as evidence.
In addition, since you are a designer, you have the copyright of the design (it is better if you have the registered copyright, otherwise you have to prove that you have the copyright, and the time is earlier than the patent application date), then they infringe on the prior rights. However, if it is enlarged, it will be more troublesome, because according to the provisions of Article 17 of the Copyright Law, the ownership of the copyright of the commissioned work is agreed by the client and the trustee through the contract. If the contract is not clearly stipulated or concluded, the copyright belongs to the trustee.
However, the specific analysis of the specific situation depends on the specific case.