Wrong additional invoice

I got an additional account last month. After comparing it with my accounts for June, July and August it seems they never recorded my one account payment on 1/7 and then they increased the rates due to higher valuation since June, but never put the higher rate in the account for those months. I still wait for their email reply. You don't get through when calling and keep on hearing the Save Water and This City Works For You recording. They work on our nerves yes!