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I am sorry to learn about this situation.
These lawsuits are becoming more common as communications providers (cable and satellite television in particular) are more easily able to track where their services are being used.
The result of your case is going to depend entirely on the specific language in your user services agreement (the contract that accompanied the setup of your initial service from the service provider - not the installation company). This contract may have come in a digitial format, if so, I recommend printing it out, and reviewing it carefully, most of these have a specific provision or clause related to commercial use.
Some services are more restrictive than others (some prohibit installation of residential lines in commercial buildings, while others are more permissive prohibiting use of residential services in commercial settings). So you need to carefully review your specific contract.
After that, you can argue that the installation by their licensed provider is a "waiver" of that clause, but this is only a "mitigating argument" and is not going to eliminate any penalty of the contractual language.