You can't reach a storage quota if the quota is unlimited. Please note that there could be additional caps. This is normal in webhosting industry and is a well-known marketing strategy where you don't get disk space limitations but you get limits in stuff like max requests per second, concurrent users/processes, hits, bandwidth, etc. That's completely normal and please ask directly to TMDHosting about these.
Keep in mind that all shared hosting have this catch and that's why there are shared servers, VPS and dedicated servers.