[tdrp]

If you are sure that's their home IP (and that's the same person triggering the spam), and they are in your country, you should consider getting a lawyer involved.

We had a similar issue and got one involved to get the process started (I think he used CFAA abuse). The attacker stopped as soon as we mentioned lawyers (he happened to also be in the US). We would have pressed it further but the lawyer was racking up billable hours and we were not in a position to afford it.

[toast0]

If all you want is for the abuse to stop, you might reach out to the ISP's abuse contacts. All this abuse is certainly against their terms, although they may or may not consider it if it doesn't happen from their IPs.

Getting your internet cut off, even if it's only temporary, can lead to a large change in behavior.