Although law doesn't say it's illegal to do online business in house. You can only complaint to local authorities if it's affect the neighbourhood.
Heck some people even drive lorries various sizes and park in the neighbourhood and that's illegal too.
Only thing u can do is pray for their business to get off n make it big. So they move out find bigger space.
Every small business that are home run seldom or never get raid by authorities. Heck newspaper always publish stories of those who make in house cookies, nasi lemak, and etc etc etc in house.
If there no smell. No clogging drain. No noise interference u cannot complaint. That it.